Chapter 3. Application considerations 97
The following sections provide an overview of the benefits of using High Performance Switch
in an HACMP environment.
3.3.1 HACMP overview
HACMP is a tool for building UNIX-based mission-critical computing platforms. HACMP
software ensures that critical resources, such as applications, are available for processing.
HACMP has two major components: high availability (HA) and cluster multi-processing
The primary reason for creating HACMP clusters is to provide a highly available environment
for mission-critical applications. For example, an HACMP cluster could run a database server
program that services client applications. The clients send queries to the server program,
which responds to their requests by accessing a database stored on a shared external disk.
In an HACMP cluster, the applications are put under HACMP control to ensure the availability
of these applications. HACMP takes measures to ensure that the applications remain
available to client processes even if a component in a cluster fails. To ensure availability, in
case of a component failure, HACMP moves the application (along with resources that ensure
access to the application) to another node in the cluster.
3.3.2 Role of HACMP
HACMP helps you with each of the following:
The HACMP planning process and documentation include tips and advice on the best
practices for installing and maintaining a highly available HACMP cluster.
Once the cluster is operational, HACMP provides the automated monitoring and recovery
for all of the resources on which the application depends.
HACMP provides a full set of tools for maintaining the cluster while keeping the application
available to clients.
HACMP lets you:
Set up an HACMP environment using online planning worksheets to simplify the initial
planning and setup.
Ensure high availability of applications by eliminating single points of failure in an HACMP
Leverage high availability features available in AIX.
Manage how a cluster handles component failures.
Secure cluster communications.
Set up fast disk takeover for volume groups managed by the Logical Volume Manager
Manage event processing for an HACMP environment.
Monitor HACMP components and diagnose problems that may occur.
3.3.3 Physical components of an HACMP cluster
HACMP provides a highly available environment by identifying a set of resources essential to
uninterrupted processing, and by defining a protocol that nodes use to collaborate to ensure