Chapter 12. Virtualization

People don’t appreciate the substance of things. Objects in space. People miss out on what’s solid.

Jubal Early (Firefly, Objects in Space)

The word “computer” immediately brings to mind some image of machinery, perhaps a monitor and keyboard, a laptop, or a stack of servers. In each case, the image is a tangible, solid, material object. This common impression is not particularly useful in software development when the physical details of hardware are masked by additional abstraction layers. Virtualization is a term used to describe a technology that hides details and specific implementation characteristics. It applies to a range of technologies related to hardware platforms, operating systems, storage devices, and network resources. While it is not directly tied to client-server web development or any other paradigm, it is interesting because many such applications are intended for large-scale deployments built on virtualization solutions. Virtualization is a powerful concept that impacts practices related to active development, deployment, scaling, and disaster recovery.

Full Virtualization

Without virtualization, a server is defined by and limited to physical constraints. Server administrators build and configure servers with a specific set of options suited to their particular hardware and purpose. Individuals on a development team each install software and configure their machine to conform to the target server. Hardware limitations, performance bottlenecks, ...

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