HP XC System Software Administration Guide Version 3.2

2 Improved Availability
The improved availability feature of the HP XC system offers the following benefits:
• It enables services and, thus, user jobs, to continue to run, even after a node failure.
• It enables you to run new jobs.
The improved availability feature relies on an availability tool controlling nodes and services in
an availability set. The HP XC System Software provides commands to transfer control of services
to the availability tool.
This chapter addresses the following topics:
• “Purpose of the Availability Tool” (page 47)
• “Services Eligible for Improved Availability” (page 47)
• “Availability Sets” (page 48)
• “HP Serviceguard Tasks” (page 48)
• “Transferring Control of Services” (page 51)
2.1 Purpose of the Availability Tool
With the improved availability feature, the HP XC System Software transfers management of
specific services and nodes to an availability tool. During the cluster_config operation, you
define a set of nodes and services as an availability set. The availability tool manages the
configured services and the nodes, and relocates the service to another configured node in the
event of a node failure.
The availability tool is not bundled with the HP XC System Software; you must order it from
the manufacturer and install it according to the manufacturer's prescribed installation procedure.
The HP XC System Software Installation Guide provides information on the installation needs of
the availability tool.
One such availability tool is HP Serviceguard, which is shown in examples in this chapter. If you
prefer to use another availability tool, for example, the open source Heartbeat tool, you can create
scripts in a tools-specific directory to run the necessary commands. For more information, contact
the HP XC support team at:
[e-mail]
The software for the availability tools is located in a directory that the manufacturer chooses.
The HP XC System Software provides a directory, /opt/hptc/availability/, under which
tool-specific directories are created. These subdirectories contain scripts and routines that automate
the configuration and management of the availability tool on the HP XC system.
During the system startup, which is discussed in Chapter 3 (page 53), you issue a command that
transfers the control of specific services previously assigned to a node in an availability set to
the availability tool. This tool manages those services, aliases, and the failover from one node to
another.
The availability tool monitors the node health, services, and aliases. If, for example, a node fails,
the availability tool restarts the services that node was responsible for on another node in its
availability set.
Before reconfiguring the HP XC system, you must issue another command to remove its aliases
and to return control of the services from the availability tool to the HP XC system.
2.2 Services Eligible for Improved Availability
The following services are eligible for Improved availability:
• dbserver for the Command and Management Database
• lvs for the Linux Virtual Server
2.1 Purpose of the Availability Tool 47