HP XC System Software Administration Guide Version 3.1

2.3 Availability Sets
A set of nodes is designated as an availability set during the configuration of the HP XC System Software.
These nodes provide failover and failback functionality. One node in the availability set is typically the
primary provider for the service. When the availability tool senses that the node has failed, the other node
in the availability set assumes the function of that service for the same availability tool.
NOTE: For the HP Serviceguard availability tool, each availability set becomes an HP Serviceguard
cluster.
A node must be exclusive to its availability set; that is, a node cannot be assigned to more than one
availability set for the same availability tool.
The following sections provide information on determining which nodes comprise an availability set,
reimaging nodes in an availability set, and reconfiguring an availability set.
2.3.1 Determining Which Nodes Are in the Availability Set
Use the shownode config hostgroups command to list the nodes in the availability sets.
# shownode config hostgroups
hostgroups:
headnode: n16
serviceguard:avail1: n15
n16
serviceguard:avail2: n13
n14
serviceguard:avail3: n11
n12
This example shows three availability sets: avail1, avail2, and avail3.
2.3.2 Reconfiguring an Availability Set
Run the transfer_from_avail command, then the cluster_config utility to modify your availability
sets.
This example illustrates the use of the cluster_config utility to select HP Serviceguard as the availability
tool and assigns nodes n7 and n8 to an availability set:
# transfer_from_avail
.
.
.
# cd /opt/hptc/config/sbin
/opt/hptc/config/sbin
# ./cluster_config
The HP XC System Software Installation Guide describes the cluster_config utlity in detail.
2.4 HP Serviceguard Tasks
This section provides examples of common tasks you perform for HP XC systems that use HP Serviceguard
as the availability tool. For more in-depth information on Serviceguard, see the HP Serviceguard
documentation at the following Web site:
http://docs.hp.com/en/ha.html#Serviceguard
Each availability set relates to a corresponding Serviceguard cluster.
44 Improved Availability