HP StorageWorks XP Cluster Extension Software Administrator Guide (T1656-96035, April 2010)

operation. The interval attribute defines the time interval in which the monitor operation is executed.
The timeout attribute determines how long to wait before considering the resource as failed.
Define start, stop, and monitor operations for the XP Cluster Extension resource.
XP Cluster Extension resource dependency
A Group resource in an SLE HA cluster ensures that the member resource agents are started and
stopped in the required order. An XP Cluster Extension resource must be added as the first member
of the group. This way, all primitive resources added after the XP Cluster Extension resource are
dependent on XP Cluster Extension.
Since the primitive resources within a resource group can be failed over independently, set a collocation
constraint for each resource group ID with the last resource in the group to achieve the failover of the
entire group when any primitive resource fails.
Failover order
Use location constraints to define the failover order for a resource group.
For each node, define a location constraint with the appropriate score to prioritize the resource group
on that particular node. During failover, the cluster calculates the score of the resource group on the
available nodes, and the node with the highest score is considered the next preferred owner. For
more information, see the SLE HA documentation.
Failback option
HP does not recommend auto failback in configurations with XP Cluster Extension because the resource
failovers due to storage failure can cause resources to go into an unstable state (failover/failback
might toggle the resource between the nodes).
SLE HA provides the meta-attribute resource-stickiness to determine how much a resource agent prefers
to stay where it is. To disable auto failback, set resource-stickiness to the lowest value compared to
the other resource location constraints.
Migration-threshold
A resource is automatically restarted if it fails. If a restart cannot be achieved on the current node or
it fails to start a certain number of times on the current node, it tries to fail over to another node. You
can define the number of failures for resources (a migration-threshold) after which they migrate to a
new node. If you have more than two nodes in your cluster, the high availability software chooses
the node a particular resource fails over to.
When an XP Cluster Extension resource fails, HP recommends configuring your cluster to fail over the
resource without restarting on the local node. To set this preference, set the migration-threshold to 1.
Disk monitoring
For the situations in which disk access is lost or read/write protection is in effect due to storage fencing,
application monitoring agents, file system agents, or LVM resource agents detect the IO failure. XP
Cluster Extension does not monitor the disk access status.
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