Chapter 1. Planning and Architecture
Key topics in this chapter:
Understanding the transformation from traditional IT
The evolution of cloud computing
Definitions and characteristics of cloud computing
Example cloud service architectures
Analysis and comparison of cloud deployment models
Planning and architecture best practices
Before undertaking any transition to cloud computing, it is important to understand its basic fundamentals and how information technology (IT) has evolved up to this point. When cloud computing was just beginning, some of the terms and models were unproven concepts, promising limitless benefitsânow, weâve had the benefit of time and experience to update those concepts into real-world systems designs, deployment models, and best practices.
Transitioning from Traditional IT
IT is clearly one of the fastest and continuously evolving industries in the world. We all know that the processing power of computers multiplies every few years, storage technology doubles every couple of years, and software applications continuously evolveâusually for the better. Just as the IT industry evolves in general, so too must the IT departments within small, large, commercial, and government organizations.
In the 1960s and 1970s, only large organizations and universities could affordâor more accurately, neededâan IT infrastructure, which often comprised a centralized mainframe computer and remote terminals for access to information and computing resources. Later, organizations began utilizing smaller centralized minicomputers, and then moved toward a system of microcomputers with much larger and distributed processing power to access and manage information everywhere. As you can imagine, this had a significant impact on IT departments.
As we entered the Internet era, outsourcing and staff augmentation exploded so that IT departments could keep up with new technologies and find enough skilled personnel. Today, the IT departments in many organizations are larger than the core business functions the company actually performs or sells to their customers.
With such large and complex internal IT departments, hired consultants and IT outsourcing and augmentation, as well as the actual expense of computer assets (hardware, software, etc.), companies are wondering if they really get a solid return on investment (ROI). Worldwide economic declines are also making organizations reevaluate their business and financial models. One thing that has become clear is that unless an organization is actually in the business of providing IT services, it should focus on its core mission and customers, not on a large internal IT departments or datacenters. Taking this into consideration and comparing the benefits of the cloud, it becomes evident that transitioning to cloud computing can offer both cost savings and corporate IT right-sizing.
A Revolutionary Shift?
Cloud sales and marketing campaigns often use the term Â revolutionary shift to describe the advancements that cloud computing brings to organizations. The claim is that cloud computing is the most significant change in the industry in more than 10 years. I disagree. This is not a revolutionary shift; rather, itâs evolutionary. It is an evolution of information technology enabling a new style of IT services at a faster pace than in the past.
Looking at the IT industry from a broader perspective, the adoption and proliferation of the Internet was a true paradigm shift, and in the more than 15 years since everyone began using it regularly, there has been a steady progression of Internet or web-based technology advancement. We went from static web pages to dynamic content, and then on to hosted applications accessed via the Internet. Then, we expanded the size and domain of traditional IT services to make further use of the Internet and wide area networks (WANs), hosting more servers and applications at third-party Internet service providers (ISPs) and application service providers (ASPs)âessentially the precursor to what we now call public cloud providers.
Cloud computing, as discussed later in this chapter, takes technology and IT concepts from the past and transforms them into a faster delivery model, providing new IT services and business value to customers at a pace weâve never before seen. Cloud computing is also somewhat unique in that business value and a focus on the end consumer is now at the forefront of planning and execution. Cloud computing, in general, is not a traditional IT department or service that is often considered a cost factor but is now an accelerator of business innovation, efficiency, and service to customers.
We have all heard the phrase âcheaper, better, and faster.â I would easily confirm that cloud computing provides better IT services at a faster development and launch pace; however, there is some debate regarding the âcheaperâ part. Although automation, virtualization, and elastic services provide clear cost benefits, the effort and cost to initially deploy the necessary cloud systems does not necessarily provide an immediate cost savings.
FigureÂ 1-1 illustrates how cloud computing is really just an evolution, not necessarily a paradigm shift, contrary to some of the industry marketing hype. Note how application platforms have matured (below the line) versus the computing technology (above the line) as the industry evolved into this cloud computing era.
The Evolution of Cloud Computing
It is important to understand how we arrived at this cloud-centric point in the information technology industry. I wonât spend too much time reminiscing about the past, but there is value in understanding the origins of cloud computing. History does tend to repeat itself, and this applies as much to the computer industry as anything else. So, let me take a moment to explain how historical trends put us on this path, how we began using many of these technologies 30 years ago, and how historic IT principles are still valuable today.
Although it did not go by the name âcloud,â the concept of cloud computing was predicted in 1961 by Professor John McCarthy of the Massachusetts Institute of technology when he stated:
Computing may someday be organized as a public utility just as the telephone system is a public utility ... Each subscriber needs to pay only for the capacity he actually uses, but he has access to all programming languages characteristic of a very large system ... Certain subscribers might offer service to other subscribers ... The computer utility could become the basis of a new and important industry.1
Starting From Mainframe Centralized Compute
In the Â early days of computer technology, the mainframe computer was a large centralized computing platform with remote dumb terminals used by end users. These terminals could be compared to thin-client devices in todayâs industry, with the mainframe being the centralized cloud computing platform. This centralized mainframe held all of the computing power (the processing cores), memory, and connected storage, managed by a small operations staff for shared use by a massive number of users.
Sounds a little like cloud computing, doesnât it?
There are further similarities when comparing mainframe-computing environments to todayâs cloud. Although the mainframe was physically very large, it wasnât all that powerful by modern standards. What the mainframe excelled at was throughput of input/output (I/O) processingâits ability to move data through the system. Ideally, the mainframe systems were managed by a centralized IT staff to maintain security, account management, backup and recovery, system upgrades, and customer support, all of which are components of todayâs modern datacenters and cloud systems.
Virtualization is another concept that existed more than 30 years ago. Indeed, it was heavily utilized in mainframe computing. Multiple customers and users shared the overall system, but used virtualized segments of the overall operating system, called virtual machines (VMs). This is almost exactly what is done in todayâs modern cloud computing environments.
Virtualization and VMs are not unique to cloud computing; these technologies have existed for more than 30 years.
The basic concepts of cloud computing have been in the IT industry all along; dust off an old mainframe concepts book and you will be surprised by the similarities. Now that we have personal computers and servers with huge amounts of memory, processing power, and storage, virtualization is now even more economical and efficient, and it harnesses excess computing power that otherwise went underutilized. As we move into the next generation of cloud environments, virtualization of servers is commonplace, with the new focus being on virtualizing networks, storage, and the entire datacenter in what is called a software-defined datacenter (you can read more about this in ChapterÂ 9).
Starting in the late 1980s and into the year 2000, the industry began a huge shift from centralized computing to distributed computing. These small distributed servers held more memory, processors, and storage than most mainframes, but the internal server I/O and network were now a challenge. After 20 years of deploying countless new, smaller servers across thousands of datacenters, computer resources (CPU, memory, storage, networking) and management (security, operations, backup/recovery) are now spread out across organizations, and sometimes even across multiple contractors or providers. Many business models have actually shown an increase in the cost of managing the entire systems lifecycle. At least the cost of compute power is a fraction of what it once was due to ever-increasing performance and ever-decreasing prices.
The Move to Consolidated Computing
Todayâs Â computing environments are highly distributed, but consolidation of server farms and datacenters is in full swing. This consolidation involves deploying higher capacity servers and IT assets into small physical datacentersâproviding equal or more computing capability while using smaller, more powerful computers to eliminate inefficient legacy systems. This consolidation will eventually bring down operational and management costs, accomplishing more with fewer IT assets, facilities, and personnel, which are some of the costliest assets.
Consider what to do next with distributed computing platforms. Mobile devices (notebooks, tablets, and smartphones) already outsell desktop workstations throughout the world. Servers are being consolidated at an increasing pace and achieving densities within datacenters never before thought possible. In fact, modern datacenters are packing so many servers into each rack that, often, power and HVAC are the limiting scalability factors rather than physical space.
With smaller and less powerful (compared to a full desktop workstation) end-user devices, we are headed back to a model wherein the compute power is held more in the datacenters than at the edge/user device. This is especially true for thin-client devices and virtual desktop interface (VDI, or in âcloud speak,â Workplace or Desktop as a Service). Not that every end-user device will become âdumbâ or âthin client,â but there is clearly a mix of users who need varying levels of compute power on their edge device.
In a relatively short period of time, we have gone from centralized compute processing with thin end-user/edge devices to a highly distributed compute environment, and now weâre headed back toward centralization to a certain degreeâthis time using clouds and consolidating legacy datacenter IT assets. History is repeating itself. Letâs hope we are making some intelligent decisions and doing it better this time. Some could argue that mainframes still play a large role in todayâs IT industry, and that they were âthe bestâ business model all along.
Transitioning to a Cloud Environment
As we consolidate many of the distributed computing platforms, datacenters, and the occasional retiring of a mainframe system, it is important to realize where we are headed and why.
As I look at todayâs cloud computing environment and our immediate future, we are shifting back to virtualization and multitenancy concepts that were founded in the early days of centralized (mainframe) computing. Though these might be long-standing concepts in the IT industry, cloud computing is pushing ever upward to new heights in the areas of automation, elasticity, on-demand ordering, pay-as-you-go pricing, and self-service management and control systems.
Organizations now understand that they might not benefit from large and costly IT departments that do not directly contribute to your customers and your core mission. Outsourcing IT functions and personnel is nothing new, but cloud computing represents a new form of outsourcing, scalability, and cost control, if managed wisely. With cloud computing, the burden of building, maintaining, upgrading, and operating the compute systems is the responsibility of the provider. This gives the consuming organization ultimate flexibility and choice of providers and eliminates being locked into a single one. This results in faster deployment of services at a lower cost so that the consuming organization can focus on its core business functions and customers, not on an IT department. This is the evolution or new style of IT service delivery that has taken 30 years to achieve.
Cloud computing results in faster deployment of services at a lower cost. This means that the consuming organization can focus on its core business functions and customers, not on its IT department.
So how are chief information officers (CIOs) transforming and benefiting from cloud computing? There is clearly a reduction in the use of traditional âmanaged servicesâ and generic âtime and materialsâ IT contractors providing computer services. Cloud consumers both small and large are able to select the cloud provider, pay for the services utilized, and scale up or scale down if finances or priorities of the business change. Organizations are no longer stuck with unneeded computer systems, server farms, and datacenters, which leads to greater agility in their overall business decisions.
Here are some of the recent trends and updated benefits CIOs can take advantage of by shifting to cloud services:
Managed service contracts transitioning to cloud service providers with more scalability (up and down) and less risk to consuming organization.
Ability to slowly shift key applications and traditional IT to the cloudâmoving to the cloud does not need to be an all or nothing transition.
Increased choice and flexibility for the consuming organization by avoiding lock-in to a single provider by using a hybrid cloud deployment model or cloud service brokering.
Organizations pay for cloud usage, which is carefully monitored and measured. In previous managed services models, it was often difficult to see actual results based on IT costs.
Centralized and efficiently utilized compute resources managed by fewer personnel with heavy use of automation and consistent processes resulting in lower cost and better quality to the consumers.
Lifecycle management, upgrade, and replacement of used resources are the responsibility of the cloud provider, resulting in reduced cost, labor, time, and risk for individual IT organizations performing this task in a traditional IT environment.
Consuming organizations do not need a large number of experienced senior IT personnel, who are expensive, difficult to find, and challenging to keep. The technical staff will be able to better focus on their mission-critical applications of their businesses rather than managing commodity IT.
There are also some challenges that CIOs and business executives need to consider when moving to a cloud service:
Organizations have significant legacy computing resources (servers, datacenters, and IT personnel) that will need to be transitioned or eliminated in order to achieve the true cost savings and flexibility provided by cloud providers and services. Often these existing computing resources have not yet been fully depreciated, making the adoption of cloud computing challenging to procure. Some organizations do not necessarily see an immediate savings because of the cloud.
Migrating large mission-critical applications to the cloud can be complicated and somewhat expensive (unlike commodity IT services, which are much easier and less costly to transition). Businesses should evaluate whether their custom and legacy applications are worth the reinvestment, or if an alternative cloud-enabled service exists which might be a better fit in the long term.
Private cloud deployments do not always have sufficient redundancy in geographically diverse hosting facilities. Using multiple datacenter facilities and/or multiple cloud providers can provide improved service availability and continuity of operations.
Procurement and budgeting for cloud services is a challenge to some commercial and government organizations. Existing procurement policies might need to be adapted.
Existing security, operations, and other processes within consuming organizations need to adapt to this new cloud computing model, in which services, applications, and VMs are launched through automation.
Definitions of Cloud Computing and âAs a Serviceâ
The first thing to clarify is the use of the term âcloud computingâ in general. Throughout this book, I refer to cloud computing as âcloud servicesâ; this is actually a more accurate term. Cloud computing, although the accepted industry nomenclature, originated from the concept of hosting computer (processor, memory, storage) resources in the cloud; hence, the term cloud computing.
Though it is still a relatively new term, cloud computing has already grown in scope and meaning to now encompass applications, virtual desktops, automated deployment, service orchestration, and moreâalmost anything related to IT that an organization would want hosted and serviced through the cloud. The term used in the industry is as-a-Service which is the âaaSâ portion of a number of acronyms that have become ubiquitous in recent years, such as XaaS. This particular acronym refers to any cloud-based application or service provided to consumers. The most common models include Infrastructure as a Servce (IaaS), Platform as a Service (PaaS), Software as a Service (SaaS), all of which youâll see later in this chapter.
Definition of the Cloud
The National Institute for Standards and Technology (NIST) definition of the cloud states the following:
Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.
Although there are several companies and individuals claiming credit for first using the term âcloudâ as pertaining to cloud computing, the real-world meaning of cloud is not truly a rigid definition. Many consider the cloud just another term for the Internet, and, depending on how the term is used, that might be correct; cloud computing frequently includes providing computing resources (processors, memory, storage) over the Internet. The key to remember, however, is that cloud computing doesnât technically require the Internet: you can utilize private communications and network circuits between facilities and essentially form your own private cloud. In many situations, a combination of private WANs, communications circuits, and the Internet is what is actually used for cloud computing services. I fully define and differentiate between public, private, hybrid, and all the cloud computing models later in this chapter.
Characteristics of a Cloud
Although they began as a pure on-demand compute and storage environment serviced through the Internet, cloud services quickly expanded to include various networking, backup and recovery, platform, application, and hosted data services. There are five key characteristics of cloud services as defined by NIST (note that I have updated the descriptions of each characteristic from NISTâs original publication):
- On-demand self-service
- An organization can order cloud services with automated provisioning of the needed computing, storage, network, and applications from the cloud provider. This includes the ability to expand services or resources as needed automatically or as requested by the organization. This also entails the ability to rapidly scale up or scale down as needs change.
- Broad network access
- Cloud services are provided over any combination of private network communication circuits or the open Internet, depending on the cloud deployment model and the specifications of the cloud providerâs offering. You can make the cloud resources available to or hidden from a wide variety of computers (thick or thin client), laptops, mobile devices, tablets, and smartphones.
- Resource pooling
- Multiple users share all resources within a specific cloud deployment. The level of sharing or dedicated resources to each user can vary depending on the cloud deployment model. Virtualization of compute, storage, networking, and applications are often utilized to separate one tenant (user) from another. Access controls are in place to maintain separation of user data from all other users. The location of resources is often spread across multiple physical locations or datacenters, and depending on the cloud deployment model, the location of hosted resources might not even be known or specified by the user.
- Rapid elasticity
- You can scale out services rapidly, with increased capacity or additional compute, memory, storage, and network resources giving the impression of unlimited resource availability. You can also reduce resources when workload utilization decreases. I will define and clarify scale out versus scale up in later chapters.
- Measured service
- Services are billed on a pay-per-use basis as determined by metering of consumed resources such as compute, storage, network, or applications. You can measure and monitor all resource usage and establish potential limits, or pay-as-used expansion of resources as needed.
Even if an organization does not migrate or adopt a true cloud service, the benefits of the cloud are still desirable for on-premises, enterprise customer-owned datacenters and IT departmentsÂ .
Where Cloud Characteristics Meet Traditional IT Goals
As organizations move critical compute, storage, and application systems to cloud providers, several additional attributes or characteristics have become more of an emphasis based on recent lessons learned. Many of the characteristics in the following list apply to IT modernization trends in general even if an organization isnât yet shifting to a cloud environment:
- Real-time statistics, monitoring, and metering of services (transparency into the cloud environment)
- Organizations have transitioned some or all of their data and applications into the cloud, so some form of visibility into the cloud environment is essential for a successful experience. This includes real-time monitoring of service status, metered resource utilization dashboards, and service-level agreement (SLA) reporting scorecards.
- Self-service management
- As applications are moved to the cloud, organizations want the ability to manage their accounts and application settings without having to submit a helpdesk ticket for routine tasks. This is often an overlooked or underestimated feature of a successful cloud offering. More details on self-service management are provided in Chapters 7 and 9.
- Role-based security for multilevel administration
- User roles are defined within the cloud management system to allow placing orders, approving orders, or managing service subscriptions. These roles also define the visibility of services between users so multiple organizations or tenants cannot see one another. The roles for each tenant are restricted so they cannot change settings or order services outside of their authorized capacity and account.
- 24-7-365 support and escalation to a single provider
- Users are looking for the provider to fully support all the services and resources hosted in the cloud. Cloud providers typically provide all backend datacenter and server farm management, but the user also needs the ability to escalate real and perceived user and access issues to the provider. Low cost providers might attempt to limit a customerâs ability to call into a 24-7âstaffed support center.
- Little or no capital expenses (funding via operational moneys)
- Public cloud services normally provide services to customers with little or no up-front capital expenses, whereas private clouds often require significant capital investment. In a public cloud model, and for some managed private clouds, the provider covers the initial cost of equipment and staging, with each customer paying for usage based on an hourly, daily, weekly, or monthly rate. The provider covers all systems management, patching, and future upgrades of hardware and software. This means that customers can better utilize their money by spreading their costs over multiple years and not having to identify a large amount of funding every so many years for capital equipment and upgrades.
- No long-term commitments and the ability to easily scale services up or down as needed or consumed
- Customers often desire little or no minimums or term commitments. It is up to the service provider to set the terms and flexibility to customize those terms to meet consumer needs. Although the consumer might desire zero minimums or commitments and the ability to cancel some or all of the services with little or no notice, this represents a significant risk to the public cloud provider or private cloud integrator, which normally results in a higher price per service over a period of time.
FigureÂ 1-2 shows the NIST visual model of cloud computing. Notice how a shared pool of resources is included among the essential characteristics at the top of the diagram. The middle layer represents the cloud service models followed by the cloud deployment types at the bottom.
Cloud Deployment Models
Cloud deployment models proved to be an area of confusion during the initial years of the cloud-computing industry. TableÂ 1-1 provides a summary definition of each cloud deployment model. Later in this section, we will look at each of these in more detail, as we compare them, and review the lessons learned. Although NIST if often referred to for definitions of cloud and cloud models, TableÂ 1-1 represents a more modern breakdown of cloud deployment models.
|Cloud deployment model||Definition|
|Public cloud||A cloud service offered to the general public. The cloud provider owns, manages, and operates all computing resources located within the providerâs facilities. Resources available to users are shared across all customers. Some cloud providers now offer higher, government-compliant security upgrades, which might use physically separate resources within provider datacenters. Customization is limited because the cloud is shared across many customers.|
|Private cloud||A cloud infrastructure operated for a single organization. The cloud can be managed by the organization or a third party, and it can be hosted on premises or at a third-party datacenter. Private clouds are typically more customizable than other forms of clouds because they are dedicated to and owned by one customer organization. Many private clouds are deployed within an existing on-premises datacenter.|
|Virtual private cloud (VPC)||A variation of public cloud wherein a segmented compartment of an otherwise public cloud infrastructure is dedicated to one customer. VPC offerings bring some of the price advantages of a large public cloud provider but with a bit more customization, security, and segmentation of VMs, storage, and networking. Variations of VPC include managed and unmanaged VMs and application services.|
|Community cloud||A cloud service that provides for a community of users or organizations with shared interests or concerns. The system is managed by one or more of the organizations, by a central provider, or a combination of the two. Organizations utilizing this cloud service have shared missions, governance, security requirements, and policies. Cloud services can be hosted on-premises at the consumer organization, at peer organization facilities, at a provider, or a combination of these. This community cloud term is often used in marketing to explain the target consumers of the service, although the actual cloud might technically be a VPC, private, or hybrid cloud model.|
|Hybrid cloud||A cloud service that is a combination of two or more of the previously defined deployment models (public, private, VPC, or community). A common example is a private cloud that is connected to one or more third-party public-cloud service providers for certain applications such as emailâall integrated by using a common cloud management and automation platform. To manage multiple cloud providers, a cloud management system or cloud-broker system is required (see Chapters 7 and 8 for more details on cloud management and cloud brokering).|
FigureÂ 1-3 depicts the relationship of the enterprise (customer) network infrastructure and private (on-premises or off-premises) cloud options. When connected to one or more types of cloud providers, a hybrid cloud is formed. There can be multiple private-or public cloud providers interconnected. Many public cloud providers offer VPC and various other as a service offerings (e.g., IaaS, PaaS, and SaaS) from their public cloud infrastructure.
Analysis and Comparison of Cloud Deployment Models
Each cloud deployment modelâpublic, private, VPC, community, and hybridâoffers distinct advantages and disadvantages. It depends upon the customer requirements to determine which model or combination of models is truly the best for a given customer. Understanding these cloud deployment models is essential to begin planning your cloud transition.
TableÂ 1-2 provided a brief definition of each cloud deployment model. Now, I will focus on the unique characteristics of each one as compared to the others. Ultimately, a full assessment of an organizationâs requirements is needed in order to pick the best solution.
Although experience and industry trends show that customers have a preference for the economics provided by public clouds, it is private clouds that offer more flexibility with customized features and security. The larger the organization, particularly government entities, the more likely a private cloud will be deployedâconversely, small and medium-sized businesses often cannot afford to purchase or build their own private clouds. Many small businesses also have the advantage of little or no existing investment in infrastructure, so they can more quickly adopt cloud-hosted applications when first forming the organization.
A public cloud service is based on a cloud provider typically offering preconfigured and published offerings. They normally have an online storefront that lists all available products, configurations, options, and pricing. Because the public cloud providers are offering services to the general public and a wide variety of customers, they have implemented their own cloud management platform. The cloud platform and services offered are targeted at the widest group of potential consumers; therefore, customization of the service is normally limited.
The public cloud provider owns, manages, and operates all computing resources located within the provider facilities, and resources available to users are shared across all customers. Customization of a public IaaS application is usually limited to selecting options from a service catalog. Common options include choice of the operating system (OS), the OS version, and the sizing of the VM (processors and storage). Cloud providers often prebundle IaaS VM services into small, medium, large, and extra-large configurations, each with predefined processor, memory, and storage sizes. Customizations to ordering, billing, reporting, or networking might not be accommodated; this is a situation for which a private cloud deployment is more suitable.
Public cloud providers have also entered the virtual private, community, and even private cloud service marketâproviding more data segregation and customization for each customer rather than the legacy pure public cloud models. Some public cloud service providers are beginning to blur the lines between public, private, and hybrid cloud through integration back to on-premises enterprise datacenter-based identity, authentication, application publishing, and other services.
A very recent industry trend is public cloud providers launching new hybrid services. These hybrid services focus on integrating traditional enterprise datacenters, typically on a customerâs premises, with public cloud services. This hybrid capability makes it possible for customers to federate authentication systems, synchronize data, support both enterprise and cloud applications, and failover enterprise servers to public cloud VMs.
Some cloud providers offer higher government-level security upgrades, which might use physically separated resources deployed in a segmented compartment within the providerâs datacenters. A public cloud provider that dedicates infrastructure and services to one customer is essentially offering a VPC, but it might market this under the term âcommunity cloudâ or a brand name such as âFederalâ or âGovâ cloud. In some cases, a cloud provider might offer completely isolated and dedicated network infrastructures for each of its customers purchasing the government-compliant high-security cloud option; however, technically these dedicated cloud infrastructures would be more accurately defined as private or managed private clouds hosted within the providerâs facility.
Private cloud services might begin with the same basic cloud computing services as offered by a public cloud provider, but the service can be hosted at a customer-owned or contracted datacenter. Private clouds offer choices of the cloud services to be deployed, how much integration there is between services, how the management and operations are handled, and the level of security controls and accreditation.
Private cloud is an excellent model for large organizations that have significant existing datacenter and server farm assets, and want to slowly modernize to cloud technologies and processes. The organization can deploy a private cloud within the same datacenter(s) with a longer-term plan to migrate legacy IT systems to the cloud model over time. The customer can then transition applications and data at the discretion of its staff, augmented by IT cloud service integrator or other expertise, as needed.
As I state throughout this book, as soon as you connect a private cloud to another type of cloud (e.g., public), by definition, you now have a hybrid cloud. In addition, if we are going by strict definitions, if you connect existing traditional datacenters, server farms, or applications to the private cloud, you also have formed a hybrid cloud. For this reason, I believe almost all clouds are or will become hybrids and the terms âhybrid,â âprivate,â and âpublicâ will disappear over time.
Almost all enterprise clouds will become hybridsâusing a combination of on-premises IT, private, and public compute and application resources.
Public and Private Models Compared
Arguably, the first public cloud service provider to achieve wide acceptance and scale was Amazon Web Services (AWS). This is an example of a true public cloud compute offering, with all the key characteristics and benefits of cloud services. Many other providers have built or are building their own public cloud offerings to provide similar capabilities. The key benefits that organizations achieve from using a public cloud are not being questioned here, but there seems to be a misconception about private cloud computing when organizations evaluate and select a provider or deployment model.
Most small and medium-sized businesses (also referred to as SMBs) do not have many choices in selecting their cloud deployment model due to their size, limited budget, internal technical expertise, and needs. Often a public cloud service offering is adequate and cost effective compared to purchasing or deploying a private cloud. For larger organizations that have size, complexity, and unique requirements, a private cloud service is often more suitable. Of course, a private cloud involves deploying the cloud services either within an on-premises datacenter, or hiring a vendor to configure a dedicated private cloud for the organization. This usually costs more money to deploy, but has significant advantages, the most important of which is the ability to customize the private cloud service to meet the organizationâs security, operational, financial, and other unique requirementsâsomething a public cloud service cannot offer and SMBs often cannot afford.
In my experience, most customersâlarger organizations and government entities, in particularâdesire the flexibility and scalability of public cloud offerings. Unfortunately, their unique requirements almost always force a private cloud to be considered in the end. These unique requirements, difficult to accomplish using public cloud, include customizations in the procurement, security, operational, reporting, and governance processes. Only private cloud deployments have the ability to highly customize the cloud service to meet customer requirements. Typically, the larger and more complex the customer, the larger and more complex its list of unique requirements will be. For this reason, it is important to discuss early in the planning process all requirements and their level of priority.
As new cloud customers see the potential uses and features, there is a tendency to ask for extensive Â customizations. Private clouds allow for more customization, but is the cost really worth it to manage one-off unique cloud platform configurations in the long run?
TableÂ 1-2 compares private and public cloud capabilities. It does not include community, virtual private, or hybrid, because these are really just variations of private and public.Â Â Â
|Capability||Private cloud||Public cloud|
|Service catalog||Customized to customer needs||Established by provider|
|Billing and reporting||Ability to integrate with corporate billing systems||Preestablished billing and reporting; no integration with corporate billing systems|
|Service-level agreements (SLAs)||Often customized per customer requirement||Established by provider|
|Granular resource metering||Granular metering of resources||Established by provider|
|Infrastructure servers||VMs and physical servers||Normally only VMs offered|
|Security||Customized enterprise-class security||High but standardized security; rarely customizable per customer|
|Service offerings||Customized to customer needs||Established by provider|
|Self-service control panel||Customized to customer needs||Limited|
|Operations and management||Performed by provider, customer, third party, or a combination||Performed by provider|
|Security management, monitoring, and accreditation||Performed by provider, customer, third party, or a combination||Performed by provider|
|Elasticity and scalability||Unlimited, based within the limits or size of compute resources||Unlimited, service level guaranteed|
|Time to provision||After initial setup, minutes to hours||Minutes|
|Support||Dedicated account support||Optional support from provider or reseller/channel|
|Professional services||Transition, migration, support, and implementation services||Limited customization services; migration and other services available from provider or reseller/channel|
|Management services||Full application, database, and platform management services||Limited application and database management services|
A hybrid cloud uses multiple cloud servicesâany combination of public, private, community, and traditional IT (enterprise) datacenters. A theme throughout this book is the trend for private clouds to be a baseline for many organizations and eventually extended services to one or more public cloud XaaS offerings to form a hybrid cloud. Technically, when you connect one cloud to another cloud, or you connect to legacy datacenters and applications, you then have a hybrid cloud. Industry and early cloud adopters have learned that it is wise to implement a cloud management system with embedded hybrid capabilities to integrate multiple cloud providers and legacy customer IT assets. The cloud management system (this is fully defined and discussed in ChapterÂ 7) is the centralized ordering, automation, and reporting engine that integrates each cloud service, integrated module, or application.
As customers push the limits of what a public cloud is able to offer, or implement a private cloud, the immediate needs often fit within the combined features of both. In the real world, even the newest private cloud customers just starting out can already see potential uses for a hybrid cloud; they just arenât ready for it yet. Although public and private clouds are the dominant models deployed today, expect to see hybrid clouds become the norm. Hybrid clouds will become so commonplace across most organizations and datacenters that the terms private and hybrid cloud might disappear in the future.
Many hybrid clouds begin as a private cloud that later extends integration to use one or more public cloud XaaS offerings. There is also a new emerging trend for public cloud providers to do the reverseâusing the public cloud platform to integrate back into legacy enterprise datacenters and private clouds. The concepts are the same but the lines between private, public, and legacy datacenters continue to blur as hybrid clouds evolve.
Motivations to implement a hybrid cloud are numerous; primarily, customer organizations might fit within one cloud model (public, private, or community) initially, but future needs to extend their cloud, service, integration, or data sharing with third parties force expansion into a hybrid cloud deployment. Rather than individual management and operations of multiple cloud providers, it is preferable to use a single cloud management system to manage or broker between cloud providers, retaining only one platform to manage all financial, ordering, procurement, automation, workflow, security, governance, and operations in your organization.
After a hybrid cloud service is deployed, the ability to take advantage of the best of breed software applications and XaaS cloud providers is increased, but management of the overall cloud solution is still crucial. Although a customer can purchase cloud services from multiple cloud providersâone hosting a public cloud service, another a private oneâpurchasing multiple services from different cloud providers requires managing each cloud provider separately. You would use each cloud providerâs management portal for ordering, billing, reporting, and so onâmultiplied by the total number of cloud providers to which you have subscribed. A hybrid cloud management solution is unique in that all cloud services across any number of cloud providers are all managed through a single management portal. All ordering, billing, reporting, and cloud operations are managed through the centralized hybrid cloud management platform. The level of development and multiprovider integration to create a unified hybrid or cloud broker platform is significant, and it is highly recommended that no individual customer try to develop a system internally.
A community cloud service provides for a community of users or organizations with shared interests and concerns. Each member organization in a community cloud can host some portion, or application(s), that all departments of the organization can use. Some departments might have the same offering, which can be pooled together for capacity, load balancing, or redundancy reasons. A community cloud can create cooperation between organizations while reducing costs by sharing the infrastructure, operations, and governance.
Organizations utilizing this cloud service would ideally have missions, governance, security requirements, and policies. Cloud services can be hosted on premises at the consumer organization, at peer organization facilities, at a provider, or a combination that allows sharing of the costs and ongoing management. Trends over the past few years indicate limited adoption of this community modelâlargely because the deployments require an extensive and deep long-term relationship between multiple organizations in order to build, govern, and operate themâthis has driven some organizations to consider VPC as an alternative model.
Some cloud providers offer a specialized, community cloud offering. Community cloud is often used as a marketing term to explain a targeted group of customers, such as government public sector organizations, although the actual cloud is technically a VPC, private, or hybrid cloud model.
The primary concern with a community cloud is how the cloud is managed. Standards of communications, cloud management systems, and the services offered need to be agreed upon and upheld across multiple departments or organizationsânot just initially, but for many years. This is where business challenges begin to reveal themselves. What happens if, in the future, one of the community cloud departments or organizations changes their business, budget, security standards or other priorities? What if that department was offering critical resources to the community cloud that will no longer be available at the same level as originally agreed upon?
The critical factors to consider in a community cloud are less technical; instead, the focus is on business process, stability, and cooperation-based considerations. Letâs take a look at some of these operational and business challenges:
- Shared ownership
- Is one of the members of the community cloud in charge of the overall management and governance of the system? Decisions by committee are often difficult, so who is the ultimate decision maker if all parties cannot agree on something?
- Shared resources
- If one member of the community cloud hosts a critical service that everyone else uses, what happens if the service doesnât meet the reliability, operational, or cost factors to which everyone originally agreed? What can one member of the community do to ensure that problems are rectified? What if one member of the community has its budget changed or business realigned and can no longer host that portion of the cloud? Transitioning can be expensive, complicated, and disruptive to ongoing operations.
- Cloud management
- A successful cloud is a cloud that has a single management system with both provider and end-user control panels. All members of the community cloud will need to either agree on a single management platformâa considerable challenge in and of itselfâor agree upon a universal standard for application programming interfaces (APIs) and integration. Even if standards are agreed upon, actually stitching together the final cloud management system to look and function as a truly integrated solution is a huge undertaking.
- Procurement and chargeback
- Which member of the organization first builds or hires a cloud integrator or provides seed funding? The methods by which one department or organization procures the cloud service might not match other departments. If different organizations host different portions of the cloud service, how are funds exchanged and granular resources (e.g., processor usage, memory, and storage) metered and charged back to each agency, department, and project?
- Will all members of the community cloud be able to agree on the security posture and accreditation of the system? If the information system security officer (ISSO) for an individual department or organization is told in his job description that he is responsible for the systems used and deployed by his organization, is that ISSO going to accept a security accreditation of the community cloud that was done by another agency? If unanimous agreement between all ISSOs across all organizations is the goal, this is even more difficult. What about ongoing security operations and monitoring? Who is responsible and how do information, threats, and mitigation activities get back to the individual department ISSOs? Finally, data privacy standards often change or are dependent on end-user locations or the type of data.
Cloud Service Models
There are several widely accepted âas a serviceâ models in the industry (and as defined by NIST). Each service model is briefly defined in TableÂ 1-3, and then I detail each service model with real-world examples, architectures, trends, and lessons learned.Â Â Â
As the cloud computing industry and customer adoption has progressed, additional âas a serviceâ (what I call XaaS) models have been coined. Most of these new XaaS models actually fit within one of the three aforementioned core definitions. Many cloud service providers started out with clearly defined cloud services such as IaaS. Today, the service lines have blurred with public cloud providers and enterprise private cloud owners now deploying numerous platform and software services.
Although Â I would like to provide you with example cloud service providers for each of the services listed in TableÂ 1-4, there are just too many providers, with a good number of them regularly adding more of these services to their portfolio. This has and will continue to blur the line between public cloud providers because most will claim to provide many of these services; however, the quality and completeness of the services will vary widely. Finally, there are many cloud providers that have decided to offer and focus on only one cloud service, such as Salesforce.com, which offers CRM. Compare this to public cloud providers Microsoft and Google, which initially launched email-centric cloud services (Hotmail and Gmail, respectively) but have significantly expanded to numerous IaaS, PaaS, and SaaS offerings.
In the following sections, I go into more depth on each service model, provide architecture examples of how the systems work, and present some case scenarios of real-world cloud service offerings available in the market today.
Infrastructure services are the most common offering for public cloud providers. Staging IaaS in a private cloud requires a certain amount of initial investment but is often the starting point of the private cloudâadding SaaS and PaaS applications after the basic IaaS compute and storage services are in place. A basic IaaS offering provides VMs with either specific fixed or dynamic and VM sizing options.2 Cloud providers might offer multiple VM sizes and OSs at fixed prices per hour, day, week, or month. The cost per VM rises as the amount of processor, memory, and storage increases. Note that one providerâs definition of a processor unit might not be the same as another provider in terms of performance or speed. In a dynamic resource pricing model (for more information on this, see ChapterÂ 5), the customer is charged a fee per unit of processor, memory, and storage which are more configurable and can afford more scalability than fixed-price IaaS offerings.
Public cloud providers often preconfigure specific offerings, such as VMs; however, the exact processor, memory, and disk space allocated to each VM might not be the same as other providers, so price comparison is not always easy. In fact, some public cloud providers have seemingly intentionally confused their VM configurations, VM size pricing, discount levels, transactions fees, and other metrics to obfuscate their true real-world costs to consumers. The key features you should be looking for are fixed or dynamic sizing, costs for expanding or increasing resources, and the ability to control your VMs through a web-based control panel. High-quality service providers will have an extensive self-service control panel that puts the consumer in control of the VMs, with the ability to reboot, resize, and potentially take a snapshot and restore them. Also, be sure to examine the SLA and any guarantees of system availability.
When it comes to flexibility of options, your public IaaS provider should give you the ability to select your preferred OS, and possibly several versions of each OS to suit your needs. The agreement should clearly specify if backup and restore services are included, or if there are additional charges for those. An advanced feature that might be available is the ability to define your own subnetworks, load balancers, and firewall services.
Although public cloud providers offer a menu of fixed and variable-priced IaaS options, deploying your own private cloud will provide more customization, procurement, and security features unique to your organization. TableÂ 1-5 presents a comparison of features for a typical public cloud service versus what is typical of a private cloud. It is important to note that public cloud providers are constantly enhancing their offerings and self-service capabilities, so the differentiation between public and private clouds pointed out in TableÂ 1-5 does not represent every situation and cloud provider.
|Selection of OS|
|Choice of VM size (CPU, RAM), storage/disk|
|Ability to dynamically expand resources (CPU, RAM, disk) as needed|
|Ability to configure load balancing, firewalls, and subnetworks|
|Ability to define backup schedule and perform self-restores|
|Self-service control panel to manage VMs|
|Provide OS patches and version upgrades|
|Ability to select from multiple backup and restore schedules and retention times|
|Ability to select from multiple tiers of storage performance (e.g., high-transaction solid-state disks, slower file-based storage)|
|Ability to manage multiple groups of VMs with separate administrators, operators|
|Ability to customize OS templates|
|Ability to customize metering, billing process, ordering/approval process|
|Ability to install custom OS versions or customer-defined custom OS|
|Meet consumer-specified security controls|
|Consumer has visibility into security logs, real-time security threats, and activities|
|Consumer has detailed real-time view into cloud operating, statistics, metering, and performance|
|Ability to specify where data is stored (by country or datacenter facility)|
|= Typically available||= Not typically available|
IaaS applications are defined by the provider in public clouds; the consumer is pretty much limited to the OS templates and versions and standard configuration options the public provider allows. As a part of a larger group of public customers, your ability to customize the offering is limitedâapplications and settings within the OS that is installed on the VM itself are the only aspects over which you would have complete control. A public cloud provider might allow you to create or import your own VM templates. Private cloud services are essentially a unique instance of the cloud service; you can customize them to a much greater degree.
Architecture of IaaS
The typical architecture of an IaaS application involves the creation of one or more server farms within multiple datacenters. The server farms each contain high-density blade servers in order to fit as many physical servers in a single rack as possible. Racks are installed in numerous rows, each one having at least two redundant power distribution units and cables into the datacenter power plant. The power plant also has various power backup resources, such as uninterruptible power supplies, batteries, and backup generators. ChapterÂ 3 contains details on architecture, design, and deployment of datacenters, server farms, and cloud infrastructure.
Multiple pools of servers or server farms are often located in the same datacenter both for expansion and local failover due to maintenance or continued operations during a hardware failure. For most large cloud providers, secondary datacenters are also deployed, as a geo-redundant system for both maintenance and facility-level failure protection. The cost of the datacenter facility, heating and cooling, power, and operations personnel are significant enough by themselves that most organizations heavily consolidate or avoid building them entirelyâyet one more reason to use a cloud provider, instead.
Shared within the racks, or nearby, are the disk and storage systemsâoften in the form of a SAN or equivalent storage system. The storage systems are normally scalable independent of the server racks and utilize their own technologies to handle data de-duplication, thin provisioning, backup and recovery, snapshots, and replication to secondary datacenters. I will not spend a lot of time on SAN technologies here (you can see ChapterÂ 3 for that), but these modern storage features afford the cloud provider significant cost savings through technology innovations and the sheer volume and quantity of storage. These savings are passed on to consumers of cloud. These costs are often lower than anything an individual consumer could negotiate and deploy on premises.
Within each physical or blade server in a rack, the cloud provider will have a virtualization hypervisor such as VMware, Microsoft Hyper-V, Citrix, or KVM. The configuration of these hypervisors is normally hidden from consumer visibility by the cloud provider. A cloud provider has significant ways to share each physical server across multiple customers; one physical or blade server can host as many as 20 to 50 customer VMs, each one having its own OS, applications, and disk storage allocation. The cloud provider can use advanced hypervisor configurations to automatically scale up processors and memory as needed to the VMs based on workload and usage. Additional tools give the cloud provider the ability to failover one VM to another physical server within the same rack, a separate rack, or even across datacenters, all without the customer even knowing the shift occurredâthis is called high availability. This is a perfect example of the technologies within the cloud architecture that benefit both the cloud provider and ultimately, through cost savings and reliability, the consuming organization.
PaaS is often confused with IaaS. PaaS combines the basic VMs and infrastructure from the IaaS model and adds software preconfigured in the VM to create a platform.
One example of a PaaS offering is a VM preconfigured with a database management system, all ordered via a single service catalog item. Platforms often consist of multiple VMs that form a multitiered application stack. Using the database example again, a multitiered application might consist of two frontend web servers, two application servers, and a clustered database serverâsix VMs in total, configured as one application platform or PaaS offering. Note that you can also classify the hosting of web pagesâsometimes across numerous datacenters and providers called content delivery networks (CDNs)âas a PaaS offering.
The PaaS cloud service provider has already done the work of properly sizing the VMs and installing the OS, application software, and tools necessary for the customer to begin using the system immediately after provisioning. Technically, a customer could have ordered one or more VMs from the list of IaaS offerings and then installed its own database software, applications, and other tools; however, this requires technical expertise and time on the customerâs part. Even more important is that in a PaaS offering, the cloud service provider now manages the entire platform, not just the OS, so all upgrades, patches, and support are handled by the cloud service provider. This is what makes PaaS unique compared to an IaaS offering.
FigureÂ 1-5 demonstrates how the cloud provider has more operational responsibilities for PaaS and SaaS applications compared to IaaS.
SaaS includes many types of applications such as commercial off-the-shelf (COTS), open source, cloud providerâproprietary, and customer owned or developed. The application along with its required server, storage, and network infrastructure are hosted by the public cloud provider or optionally on a customer or third-party premises. Typical examples of SaaS include email services, collaboration, instant messaging, document libraries, and CRM.
Organizations often have too many applications to list, but it is important to remember that without significant recoding many legacy applications are not suitable for deployment in a cloud service. Many months or years of application transformation (a topic worthy of its own book, but I cover this in ChapterÂ 4) are often necessary. In the meantime, there are techniques used mostly in private, community, and hybrid clouds that make porting of simple legacy applications possible while a full recode of the more complex legacy applications is performed.
Because each application in a SaaS offering is unique in its infrastructure requirements, licensing, cost, and deployment models, there is no single solution that cloud providers use. A smart cloud provider takes advantage of as much of the IaaS architecture described earlier. This means using a shared-storage system or SAN, virtualization of server hardware when possible, and redundancy and load balancing across multiple server farms and datacenters. SaaS cloud providers can implement dedicated server farms and applications for each consumer organization, but this is not nearly as cost effective as sharing a single instance of each application across a multitenant configuration. Additional benefits include the ability to deploy bug fixes quickly and upgrading software to the latest version, precluding the need to support numerous older software revisions.
Depending on the type of software, the manufacturer, the built-in security controls, and login and authentication systems, the cloud provider uses a combination of native software tools and custom-developed programs to maintain separation (or multitenancy) between consumer organizations. This means one consumer cannot see data, user accounts, or even the existence of any other consumer.
Public cloud providers include very economical licenses (after a significant amount of renegotiating with the software vendors) for software used in their SaaS offerings. In some cases, this is no mean feat, because the licensing models of software vendors do not often allow dynamic license expansion and contraction. In an average cloud system, the cloud provider takes on the responsibility of purchasing and maintaining a pool of licenses for all software products, and often across dozens of software manufacturers. This means that consumers do not need to bring their own licenses or purchase traditional software licenses of their own; they simply ârentâ a license from the cloud provider. In a private cloud deployment model, you might not have as much leverage with software vendors to negotiate pay-per-user elastic licensing; however, itâs possible that you will be able to use existing Enterprise License Agreements (ELAs) that your organization might already own and prefer to maintain.
TableÂ 1-6 shows a comparison of the common capabilities and limitations of public cloud SaaS applications compared to traditional IT or private cloud application hosting. As you can see, a public cloud SaaS offering might not provide the same level of customization or features as a traditional IT or private cloud based-applicationâthis is mostly because the public cloud SaaS application is a shared system, whereas private and traditional is dedicated to one customer.
|Backend infrastructure (server, compute, disk) provided and managed by cloud provider|
|Licenses furnished by provider, included as part of the per-user fee to consumer|
|Application updates and patches by provider|
|Define backup schedule, perform restores|
|Self-service control panel to manage VMs|
|Provide OS patches and version upgrades|
|Selection of additional storage or application options||Limited|
|Ability to customize application features||Limited|
|Host legacy customer applications and maintain app operations|
|Ability to select from multiple tiers of storage performance|
|Ability to customize metering as well as billing, ordering, and approval processes|
|Meet consumer-specified security controls|
|Consumer has visibility into security logs, real-time security threats, and activities|
|Consumer has detailed real-time view into operating statistics, metering, and performance|
|Ability to specify where data is stored (by country or datacenter facility)|
|= Typically available||= Not typically available|
One key aspect of SaaS offerings is that the cloud service provider manages the entire system, including all servers or VMs, the OSs, and all the applications. Technically, a customer could order an IaaS offering (plain VM with an OS loaded) and install its own software applications, but then the customer is responsible for all upgrades, patching, and support. With a true SaaS offering, the cloud service provider handles all management of the system, including all future versions/upgrades. For a diagram of provider responsibilities across IaaS, PaaS, and SaaS offerings, refer back to FigureÂ 1-5, earlier in this chapter. Across all cloud services, the consumer still has the ability to perform some configuration within certain limitations that the provider and application allow.
Other Cloud Service Subcategories
So far, IaaS, PaaS, and SaaS are the primary categories of cloud services that weâve explored. Within these primary categories, there are numerous cloud services that have their own âas a serviceâ names; technically, however, they are individual use cases or applications that fit within the definition of IaaS, PaaS, or SaaS.
Workplace as a Service
To be accurate, Workplace as a Service (WPaaS) fits within the definition of an IaaS or even a PaaS. Similar to IaaS and PaaS, numerous physical servers, each with a hypervisor system, are pooled to offer a multitude of VMs to the consumers. These VMs are very similar to the VMs in an IaaS offering, except that they are normally installed with a desktop OS rather than a server-based OS. Microsoft Windows or Linux are common desktop OSs. Citrix is one of the most popular hypervisor technologies for WPaaS. Desktop as a Service or virtual desktop interface (VDI) are other names that cloud providers use for these hosted virtual-desktop platforms.
The VMs in a WPaaS solution also include application software for users such as Microsoft Office. Users log on to the VMs through the Internet or other WAN communications circuit and essentially âtake controlâ of the virtual desktop. All processing (compute, memory, and storage) is actually running within the cloud service providerâs datacenter with only display, keyboard, and mouse activity transmitted over the network. The end user functions as a thin client using a desktop, notebook, tablet, or other thin-client terminal.
The applications that are shown for one consumer organization, or subset of users within an organization, might be different from other users. This is done through the configuration of roles and profiles in the OS and application software. Based on the userâs logon credentials, certain applications are available and preinstalled on the virtual desktop. There might be several levels or types of users that each consumer organization defines, such as Executive User, Knowledge User, or Task User. In this example, an Executive virtual desktop would have all available software installed, and maybe a higher level of storage and compute or memory, compared to that of a mid-level Knowledge user. A Task user might be a specific role for end users who only access a single program rather than an entire virtual desktop with a suite of applications. Of course, the cost that the cloud provider charges will depend on the definition of the users, the size of the VMs, and the cost of the software licenses for the apps.
In a public cloud service model, the cloud provider is responsible for all management and upgrades to the OS and all applications. In a private cloud model, the organization that owns/operates the cloud could take on full OS and application upgrade responsibility or allow participation from end-user departments to manage portions of the application stack or user profiles. The consuming users need only load the thin-client or remote desktop software tool that enables the connection through the cloud to the virtual desktop server farm.
You can also integrate custom applications into the virtual desktop solution, but this usually requires the cloud provider to host the application itself and assume full responsibility for the application lifecycle, including all management and future upgrades. Because the customer already owns the application, cloud service providers might not charge a license fee for these homegrown applications, but they will normally charge fees to manage them (e.g., backup and restore, upgrades, and patches).
Microsoft Virtual Desktop Infrastructure, Citrix XenDesktop, and Vmware Horizon View are some of the top desktop virtualization software platforms used by cloud providers or organizations with private clouds. Each of these software vendors has multiple product differentiators both at the server and end-user level. There are many other desktop virtualization systems that public cloud providers utilize behind the scenes, and they do not always publish which software platform they use.
Application publishing uses similar technology as the aforementioned WPaaS. This service has one or more individual applications available to end users instead of the entire OS desktop interface. This is ideal for several types of situations, including the following:
Task workers who only need to run one application that they use all day long (thereâs no point in presenting a full virtual desktop OS for these users).
Application publishing for very large or legacy applications that need to be available to a large number of end users but are easier to manage when in the cloud rather than installing them on every end userâs computer. By publishing an application, end users can click an icon on their full desktop OS and run the application from the cloud. The application technically runs in the cloud with display, keyboard, and mouse activity transferring over the Internet. The application is never installed on the end userâs desktop computer, so whenever the application is updated, the user gets the latest version immediately; thereâs no need to upgrade it on every end-user desktop.
Mobile devices (e.g., tablets and smartphones) are now very common and also greatly benefit from application publishing. This app publishing is particularly important for mobile computing because end users rarely turn their devices over to an IT department to install or routinely update software, especially when the mobile devices might be owned by the end user, not the company.
Application publishing is quickly gaining popularity with some public cloud providers such as Microsoft Azure. Azure, as described in ChapterÂ 5, has recently added a new service called RemoteApp. With RemoteApp, administrators can select any cloud-hosted applications that users are allowed to use. End users can run the RemoteApp application on a Windows, Macintosh, Android, iOS, and Windows Mobile deviceârunning full Microsoft Office applications, for example, on their desktop or mobile devices. Behind the scenes, these applications are fully run on the cloud servers within Azure with only the user interface transmitted to the end userâs desktop or mobile device. This RemoteApp service is a good example of a cost-effective way to manage a wide variety of end-user devices and enterprise applications at a very low cost. Because RemoteApp is a cloud-based service, organizations pay only for the actual services used, and Azure automatically scales servers up and down to keep up with utilization.
The future of application publishing holds huge promise. There is only one major downside to using it: users must be connected to the Internet or connected to the cloud in some way to use their applications; there is no offline use. There is some newer application publishing software that incorporates an offline capability. These applications will still run over the cloud and require access via the Internet, but it will save a copy of itself on the local desktop or mobile device the first time it is run. After this background copy is finished, the next time the end user runs the application, it will still try to run the application online, but if there is no connection to the Internet, the application will run locally. When the user next runs the application while connected to the cloud, if the application has been updated to a newer version, it will still run remotely while quietly updating the stored version for offline use.
Development and Test as a Service
A Development and Test as a Service (also called Dev/Test) offering technically fits within the definition of PaaS with several unique features that facilitate application development, testing, and automated release management efforts.
Customers benefit from a Dev/Test by being able to quickly launch new VMs within minutes, perform testing of an application, and turn off the Dev/Test service when it is no longer needed. Because all the servers are hosted with VMs in the cloud, the consuming organization does not need to prepurchase and deploy a dedicated server farm, sitting idly when an application development team has finished their work, or between application releases. Dev/Test teams often utilize numerous VMs residing in on-premises private cloud facilities or in a public cloud. Then, there are multiple work streams, multiple development teams, testing and quality assurance teams, and multiple versions of each application being developed simultaneouslyâall of this benefiting from the elasticity and pay-as-you-go features of a private or public cloud.
Specific features of a Dev/Test environment are detailed in the list that follows (the basic offering and systems architecture is the same as IaaS, which means there is a pool of physical servers, each running a hypervisor system providing capacity for hundreds of thousands of VMs on-demand):
- Isolated Dev/Test network
- Many organizations have strict policies and procedures that must be followed whenever a new VM or application is installed in the production network. In a Dev/Test environment, the application developers need to have the ability to quickly bring VMs up, reconfigure them, install application code, test the code, and then shut the systems down. All of this is performed regularly during the time a development team is creating its application for production release, and can last for months. For the developers to have this freedom without being restrained by paperwork, isolating the Dev/Test network from the production network using a firewall is a common technique.
- Even if both the production and Dev/Test networks are hosted by a cloud provider, organizations want to protect their production network from untested or new application code. Some Dev/Test systems provide a separate subnetwork for each application project, so that one application development team cannot interfere with others. This protects other development teams from such possibilities as an untested, ârun-awayâ application clogging the network with traffic.
- Multiple versions, snapshot, and rollback
- The ability of the application development team to make a backup or snapshot of a VMâor the entire environmentâwas briefly touched on earlier. This snapshot saves a copy to disk and makes it possible for the development team to run numerous copies of its system. It can perform testing against a copy of its environment rather than on a single instance, and avoid potentially messing it up. If testing is successful, a rollback of the environment is not necessary, and this set of VMs would become the new baseline release. This feature is a very significant benefit of using VM/hypervisor technology, and by paying only for the usage of VMs and storage, the consuming organization truly benefits from on-demand just-in-time provisioning and shutdown in developing its application projects. Creating numerous copies of VMs with many different versions can consume a great deal of storage space; thus a great deal of storage space can be required by the system. To keep costs low, delete older copies that are no longer needed.
- ALM tools
- Many application development teams use ALM tools to help coordinate and facilitate the development process. You can install these tools on one or more VMs within the cloud, alongside the application VMs and database systems. The application development team uses the ALM tools to track its project milestones, maintain a code repository, perform QA checks, perform load testing, and promote application revisions from Dev/Test into production. Popular ALM suites in the industry include offerings from Microsoft, IBM, and Hewlett-Packard. There are also smaller tools, and even open source tools, that an application team can use. Additionally, some cloud service providers that offer Dev/Test will offer the ALM suites as an optionâthis is a nice benefit, because the ALM suite will already be configured and ready for use upon ordering, and the licensing costs the cloud provider charges might be less than a single customer would pay for its own copy.
- Promotion into staging and production
Some Dev/Test offerings provide the application development team with the ability to promote individual or multiple VMs to the next phase of the application lifecycle. For example, when all testing of an application release is completed in the Dev/Test environment, clicking a âpromoteâ button would automatically copy or move the VMs to a staging or production network within the cloud providerâs datacenter, facilitating an Agile software delivery and continuous application delivery automation (for more information about this, refer to ChapterÂ 4). An additional benefit to the customer is the ability to launch a new release of its application into production while maintaining the availability of its Dev/Test environment for the next release. If the Dev/Test VMs are no longer needed, they can be de-provisioned and the customer stops paying for them. FigureÂ 1-6 shows a Dev/Test network with multiple isolated network segments for development, testing, and production.
- Pricing for Dev/Test offerings is typically in the same range as multiple VMs within an IaaSâany ALM tools you purchase will of course incur additional charges. You pay either a fixed fee and/or variable fees each day, week, or month for using the VMs and storage. You can pick your VM sizes, OS templates, and storage amount just as you would in production. You often donât need as large a VM in Dev/Test as you do in production, because you are usually not running simultaneous production users (unless you are using your Dev/Test service for load testing and quality assurance). This can result in savings by ordering smaller, less powerful VMs in Dev/Test.
- FigureÂ 1-6 shows a Dev/Test network with multiple isolated network segments for development and testing and production. In theory, there could be even further network segmentation for the Dev/Test and production portions of this notional architecture and for each unique application or development team. Also, FigureÂ 1-6 intentionally does not indicate whether this is a private or public cloud. Many organizations utilize public cloud for its significant elasticity and no initial investment in IT assets that a private cloud requires. Some organizations use a combination of public and private clouds to do their development testing and hosting of production applications using ALM tools to replicate, synchronize, or promote development code between environments.
Storage as a Service
Storage as a Service is an essential part of the IaaS and PaaS offerings because VMs need storage in order to run. Storage as a Service provides various forms of data storage, as described in the list that follows, via the cloud, which makes it possible for end users to access their data from any location, personal computer, tablet, or other device connected to the cloud or Internet. Storage as a Service provides low-cost elastic storage that expands and shrinks based on utilization. Deployment and operational best practices for storage is detailed in Chapters 2 and 3.
Storage as a Service is distinct from requesting additional storage as an option for an IaaS VM: Storage as a Service is storage sold as a standalone product. Because this storage is not connected to a specific server or VM, it can be sold and configured in several forms.
It is important to understand that cloud storage is often sold and described in terms of the type of storage being offered, such as object storage. The underlying storage method (e.g., SAN, network-attached storage [NAS], and direct-attached storage [DAS]) is not disclosed to cloud consumers. Refer to ChapterÂ 3 for details on how to build a private-enterprise cloud and use this cloud storage hardware, along with software, to create a cloud storage service offering.
These are the forms of data storage provided by Storage as a Service via the cloud:
- Object-based storage
- Object-based storageÂ is the most common form of cloud storage. It can be sold and configured as a standalone service offering without a VM. Object storage uses a specialized technique of writing data and metadata used for long-term data storage, archiving, and unique applications that benefit from this technology. Public cloud providers sell this, under various marketing brand names, for customers that want backup, archiving, and file storage services. Many popular desktop and server backup and storage applications sold to consumers are actually just frontend interfaces to object-based storage systems hosted by a cloud provider.
- Object-based storage is not a particularly high-performance storage system, but it can handle very large files (or objects) and related metadata, which is actually why it is ideal for a cloud environment. It is optimized for data that is stored once and held indefinitely. It is ideal for use cases and applications for which the network latency is unknown or might be high depending on the end userâs location, device, or network bandwidth. Object storage is capable of maintaining the connection and reliability across these nonpermanent, usually Internet-based connections.
- The cloud provider uses specialized software to present object-based storage features to the cloud consumer, utilizing the underlying SAN, NAS, DAS, or similar form of storage.
- Block storage
- Block storageÂ requires a host server or VM and is similar to a local hard drive or the default storage included with every VM ordered. You can add the storage to existing VMs or you can add it as independent volumes that the VM OS formats and manages.
- Block storage is typically capable of higher performance and is more sensitive to latency. It is typical to use block storage as the primary volume for VMs and applications within a datacenter and within the cloud provider. Block storage is also ideal for heavy read/write functionality versus object storage, which is more adept with write once/read many use cases. It is less ideal to map a block-storage volume across the Internet or slower, higher latency network connection.
Pricing for storage is usually by the gigabyte (GB) or terabyte (TB) depending on the cloud service provider and the quantity of storage purchased. Because this is a cloud-based offering, providers normally charge only for the amount of data you have utilized rather than preallocated amounts. This pay-as-you-use storage model is one of the fundamental characteristics of cloud computing.
Daily backups should be a standard feature of Storage as a Service pricing. The cloud service provider needs to maintain their SLAs as much as you need them to protect your data, so a base level of backup is normally standard and included in the price. The provider might also offer more frequent backups (including real-time data replication) and long-term data retention options.
Backup as a Service
Backup and Recovery as a Service (Backup as a Service) is a category of service that replicates data to multiple IT systems and datacenters with the purpose of recovery should the primary data be lost or becomes corrupt. Backup and recovery of servers, applications, and data is nothing new to a datacenter or IT department. In a cloud environment, there are changes in the backup/recovery hardware and processes that are needed to backup and protect a cloud environment. ChapterÂ 3 details operational best practices for cloud backup and restore.
Backup as a Service is often sold and configured in two variations described here (in both variations, the underlying service is usually object-based cloud storage; however, public cloud providers charge less for these backup services as the data is normally written once, seldom accessed/read, and stored on slow relatively disk media):
- Upgraded backup and restore options
- IaaS, PaaS, and SaaS applications normally include some default level of backup and restore capability and SLA defined by the cloud provider. Customers who need more data retention or faster recovery options might want to order upgrades to the base level of IaaS/PaaS backup.
- Depending on the service offering, platforms, or software applications, these backup and recovery options can vary widely. For example, a normal backup of a PaaS system might be performed daily by the cloud provider; however, a customer might want to have database snapshots performed every four hours. This way, during a restoration request, the data is more up to date (this is referred to as recovery point objective or RPO). There might also be a need for daily mailbox backups of the email system, rather than the entire database. This accommodates more granular restoration of data, but the cloud provider might charge more for this level of backup.
- Depending on your need, it is important to consider the cost for X years of data retention, whether the data is stored offsite from the primary datacenter(s), and how long it will take for the cloud provider to actually restore the data upon your request (this is referred to as recovery time objective or RTO). Most modern cloud providers and datacenters are moving away from tape-based backup systems, opting instead to use SANs (or equivalent NAS, object, or storage network systems), snapshot techniques, de-duplication, and disk-based backup hardware to improve the RTO (for definitions and details on these technologies, see ChapterÂ 3). If there are regulatory or legal requirements for ensuring that the backup data is held within the United States, you will need to confirm the cloud provider offers sovereign data options or consider a private cloud deployment model which offers more flexibility.
- Online backup and archiving
- This variation of Backup as a Service is unique in that the source data is usually located at an existing or legacy customer datacenter. Backup software agents or a backup hardware appliance device would be installed at each legacy enterprise datacenter. All backup software agents within the datacenter are usually already in place, but the target tape or disk system for backups is shifted to the new backup hardware appliance. This local backup appliance holds the initial backup data and then automatically replicates it to the cloud providerâs datacenter(s) over the Internet or another WAN circuit. This means that the data is backed up both locally at the original datacenter and offsite for maximum protection. The local backup appliance is usually only large enough to hold the most recent one to four weeksâ worth of data. The cloud provider hosts a massive amount of storage capacity and can retain all of the backup data for many years, depending on the customerâs needs.
- The online backup service is both very cost effective compared to a legacy datacenter maintaining large tape drive libraries and sending tapes offsite regularly. This online backup offering is also ideal for migrating data from a legacy datacenter to a new cloud provider.
FigureÂ 1-7 shows an example of an online backup architecture in which data is backed up locally within the primary datacenter but also replicated, in near-real time or via snapshots, to a secondary datacenter or datacenters. In this example, the data is transferred via the Internet but this could also be performed via high-speed private data circuits.
Other âAs a Serviceâ Offerings
Cloud providers often market additional âas a serviceâ offerings to customers. Most cloud offerings technically fit within the definitions of the IaaS, PaaS, or SaaS models. There is a tendency for cloud providers to market and advertise their services by using newly invented terminologyâsomething called Anything as a Service or X as a Service (XaaS).
The following list describes some of the unique XaaS offerings that have been coined (however, note that this is an ever-growing list, as cloud providers are constantly inventing new names for their services):
- Data as a Service
- Data as a Service is normally offered as part of a public or community deployment model, where the cloud service provider hosts a large centralized repository of information. Consumer organizations pay a fee to search for and access all of this information in the cloud. This data can be gathered and maintained by the cloud service provider, or it can be customer-specific information that just needs to be hosted in the cloud for distributed users across the world to access. Often, the cloud service provider hosting the Data as a Service operates a behind-the-scenes hybrid network that collects the data from multiple sources and provides the result to consumers for a fee.
- From a technical point of view, Data as a Service is a form of SaaS that has existed for years over the Internet, long before cloud computing became a popular term. Good examples are the LexisNexis service for legal information, or pre-Wikipedia online encyclopedias. As long as the data is useful and valuable to customers who are willing to pay for it, it can be hosted in a Data as a Service model. Data services also specialize in gathering or collecting massive amounts of data from numerous sources, formatting or indexing the data to be more useful to consumers. One difference between this data service and a website hosting massive data is that the data service offering will usually have API or database-level access rather than solely rely upon a web-based frontend. This makes it possible for data in the Data as a Service model to interact with on-premises-hosted options or other cloud service offerings.
- Customer Relationship Management as a Service (CRMaaS)
- This service is technically a SaaS offering (and in some cases, PaaS), providing clients with a customer relationship management system. These are used to track customer sales, contacts, orders, issue tracking/ticketing, and a complete history of customer transactions. CRMaaS offerings are very popular in both public- and private-cloud methodsâbefore the term became heavily utilized. Salesforce.com is an excellent example of this type of SaaS-based CRMaaS.
- Email as a Service
- Email as a Service is usually a SaaS offering providing customers with cloud-hosted email, calendar, and collaboration tools. Being a SaaS offering, the cloud provider is responsible for the management, operations, and upgrades of the entire software application, OS, and VMs that comprise the Email as a Service offering. Email as a Service offerings are popular in both public and private cloud models. Public email providers include Microsoft Office 365, Googleâs Gmail, and Yahoo! Mail, whereas private clouds might use Microsoft Exchange, IBM Lotus Notes, or Novell GroupWise.
Planning and Architecture Best Practices
Based on Â lessons learned and experience from across the cloud industry, you should consider the following best practices for your organizationâs planning.
Planning for Cloud
Planning for the transition to the cloud is the most critical factor for success. Organizations often have a significant number of legacy computing resources such as servers and datacenters that will need to be transitioned or eliminated in order to achieve the true cost savings and flexibility provided by a cloud. Organizations can chose to modernize existing IT systems with cloud-like features such as virtualization and automation, or make a plan to completely transition some or all IT applications and infrastructure to a public, private, or hybrid cloud. Planning involves technical, financial, operational, and business process changes for your IT department and possibly your entire organization:
- Business planning
- Evaluate the business needs and how IT services those needs:
Consider what applications, server farms, storage, or entire datacenters might not be critical to the mission of your organization and your customers.
Identify and prioritize by application of business functionânot necessarily by technologyâIT services and applications that are commodity functions and not unique to your company (i.e., would shifting to a cloud provider or service relieve your IT operation from this burden with equal or better services and costs?).
What could your existing, or restructured IT department better focus on if some or all commodity IT services were outsourced or migrated to the cloud? Focus on applications that are unique to your business and your customers that could benefit from increased support, enhancements, resources, operations, security, and so on.
Evaluate current contractors, temporary employees, and resource levels. Nobody is saying that a cloud service should automatically include staff reductions, but would realigning current staffing (permanent or contracted) benefit your organization as a whole?
Evaluate how the existing IT department interacts with and provides services to the overall organization. Is IT a trusted advisor and facilitator of services to the business and your customers or is IT perceived as an obstacle (for whatever reasons) to the business needs? This is a good time to reconsider how IT provides IT services, how IT might centralize (i.e., broker) IT services from multiple departments, possibly removing some legacy silos or unnecessary tiers or structures.
- Financial planning
- Evaluate the financial aspect of your current IT organization and business operations:
Analyze the cost of all current IT infrastructure systems, datacenters, applications licensing, data storage, and ongoing operational costs.
Analyze the cost of existing IT personnel, contractors, and any supporting vendors or service contracts.
Begin identifying any particular applications or legacy systems that you know or suspect are outdated, cost more to support than they are worth, and could be retired or replaced.
Include financial calculations for datacenter, network, server, storage, and application lifecycle replacements, depending on the useful service period (usually three to five years). Consider infrastructure costs for items for which warranties have expired, are about to expire, or are such a significant ongoing cost that an alternative might be considered.
Remember to include indirect costs such as power, cooling, building facilities, leased assets, or other costs that the business incurs but might not have been directly budgeted from an IT perspective (until now).
Attempt to break down all costs to a per-user and per-application basis so that you can truly understand the cost per user per month (or year) for your IT operations. This is often the most difficult and underestimated aspect of financial planningâmost organizations underestimate or simply have never calculated all of the direct and indirect financial costs.
Calculate where your major IT assets are in terms of their depreciation schedule, because this will affect your financial plans, return on investment strategy, and possibly the entire idea of transitioning to the cloud.
- Technical planning
Decide your current technical infrastructure, operational processes, facilities, equipment and software lifecycles, current staff skillsets, and effectiveness of your current IT department:
Evaluate which applications, data, or workloads are mission critical for performance, availability, and security and whether hosting on premises (enterprise IT or private cloud) is required.
Determine a draft list of candidate workloads that might be commodities and outsourced to a cloud provider (or not).
Evaluate current personnel skillsets and whether services hosted in a cloud might be more beneficial (the cloud provider likely has more specialized and skilled personnel).
Assess and document which data might be required by policy, preference, or regulation to be hosted in a particular country or region.
Which of the businessâs mission-critical applications (that your customers use) can most benefit from a dynamically scalable, elastic environment to handle spikes in the workloads or regularly expanding and contracting workloads.
Determine the security protections and risk profiles for each application or dataset.
Cloud Deployment Models
Consider which applications, data, and workloads are best suited to be hosted in a low-cost public cloud and which might require a more customizable private cloud (possibly one hosted on premises):
Decide which workloads and data could be hosted in a public cloud and any concerns or risks with hosting in a public cloud environment (regardless of provider at this point). Then, consider which applications and data are too sensitive, too specialized, or otherwise would be best hosted in a private cloud (hosted on premises or in a managed private cloud hosted by a provider).
Determine whether your existing IT organization and staff should or could manage (continue to manage?) all of the applications, server farms, networks, and storage. and which workloads could be moved to the cloud. It is recommended that the internal IT department focus on applications that are critical to your business customers and that are unique (not a common commodity IT service that anyone can host). This consideration of who will host, manage, and operate any future clouds or modernized IT services combines technical, financial, and business planning.
If there are significant requirements for a private cloud, consider whether your organization can use a managed private cloud hosted by a provider or if deploying an on-premises private cloud is required. I recommend leaving out the financial and operational considerations of this decision initially when making this assessment.
Industry trends as organizations choose cloud deployment models:
Although experience and industry trends show that customers have a preference for the economics provided by public cloud, it is private clouds that offer more flexibility with customized features and security.
Small businesses often have little existing internal IT assets and are more likely to use public cloud SaaS models to meet their needs. Many of these small businesses start out using a SaaS offering rather than building something on premises and migrating to a cloud-based SaaS.
Larger businesses and public sector organizations often have a significant number of applications and data that they determine is best hosted on premises using a private cloud. If some workloads can benefit from a public cloud, the private cloud is enhanced with hybrid cloud management capabilities so that some workloads are provisioned to one or more public cloud services.
Trends over the past few years show little adoption of this community model. The primary concern with a community cloud is how the cloud is managed. Standards of communications, cloud management systems, and the services offered need to be agreed upon and upheld across multiple departments or organizationsânot just initially, but for many years. This is where business challenges begin to reveal themselves. What happens if, in the future, one of the community cloud departments or organizations changes its business, budget, security standards, or other priorities? What if that department was offering critical resources to the community cloud that will no longer be available at the same level as originally agreed upon?
A recent industry trend is public cloud providers launching new hybrid services. These hybrid services focus on integrating traditional enterprise datacenters, typically on a customerâs premises, with public cloud services. With this hybrid capability, customers can federate authentication systems, synchronize data, support both enterprise and cloud applications, and failover enterprise servers to public cloud VMs. Consider this type of hybrid cloud (public cloud reaching back into internal enterprise IT) as a technique for early adoption, bursting, or long-term migration to a public cloud.
Development and Testing
Often the Â easiest workloads to shift to a cloud computing environment are software development and testing tasks. Considering the immediate on-demand elasticity and low cost of basic VMs in a public cloud, it is often difficult to justify the legacy method of staging and hosting your own internal servers for Dev/Test purposes.
Consider what security level, if any, that the Dev/Test environment must meet. Dev/Test environments donât usually host production data that might have security or privacy concerns. Because of this, development, coding, quality testing, and user testing utilizing a public cloud provider is a very attractive service offering.
Remember that a basic IaaS application that offers VMs is not necessarily suitable for a complete Dev/Test environment. The more robust Dev/Test environments often have ALM tools for developers to store programming code, testing tools, and the ability to promote development code to testing or production. When evaluating public cloud providers or building your own private cloud for Dev/Test purposes, consider what tools and operating systems are supported by the cloud platform.
Consider what ALM tools your company or developers utilize and whether the cloud provider will make these tools available, at potentially lower cost in a shared model, or how you can install your own copies of the ALM tools into the cloud service.
Consider implementing multiple virtual networks or subnetworks within your Dev/Test environment to simulate development and production networks. You might also want the ability to promote your Dev/Test applications into production subnetworks using ALM tools, as mentioned earlier.
Consider how you will save your Dev/Test cloud systems when there is a pause in the project. Will the cloud provider still charge for idle Dev/Test systems that continue to take up storage in the cloud? How long will the cloud provider maintain the idle (turned off) Dev/Test systemsÂ Â before deleting them?
Workplace as a Service, Remote Desktops, and Application Publishing
When considering hosting virtual desktops in the cloud, assess the users and their applications and whether they are suitable for hosting in the cloud.
Consider that most virtual desktop services do not work in an offline mode (when disconnected from the Internet or corporate network); this might require data replication back to local laptops or tablets so that users can work offline while traveling, for example.
Consider where the data will be located for your normal desktop users and applications versus those who might use virtual desktops from the cloud. How will these users interact or share the same experience if there is data held in the cloud and also data back on the internal network?
Carefully test the cloud-based virtual desktop and applications for printing capability back to a local printer wherever the end user might be located (e.g., a hotel, at home, or at a remote office location).
Consider application publishing of one or more applications for those that a large number of users need to access from any office, location, or Internet/cloud accessible device. This is often more agile and easier to accept (by end users) than a full virtual desktop environment.
Consider the IT skills and effort required to manage a full remote desktop or application publishing environment. The creation of OS images, applications, profiles, and permissions is significantânot necessarily more than would be required on an internal traditional desktop environment.Â
1 Source: Simpson Garfinkle, âThe Cloud Imperative,â Technology Review, October 3, 2011, http://bit.ly/1cCr5Ux.
2 Some providers also offer physical servers within their IaaS offering. However, these are more expensive, because the provider has less ability to virtualize, load balance, and move workloads; in addition, the provider must have dedicated physical servers idle as excess capacity waiting for customer orders.
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