HP P6000 Cluster Extension Software Administrator Guide (5697-0986, June 2011)

Recovery policy
When a resource inside the service fails, the default action is to restart the service on the local node
before the failover. In a P6000 Cluster Extension environment, it is always expected to relocate the
service during restart. To enable this functionality, set the service recovery policy to relocate.
Service hierarchical structure and resource dependency
In RHCS, a service is a collection of cluster resources configured into a single entity that is managed
(started, stopped, or relocated) for high availability. A service is represented as a resource tree that
specifies each resource, its attributes, and its relationship among other resources in the resource tree.
The relationships can be parent, child, or sibling. Even though a service is seen as a single entity, the
hierarchy of the resources determines the order in which each resource within the service is started
and stopped.
In the case of a child-parent relationship, the startup or shutdown is simple. All parents are started
before children, and children must all stop cleanly before a parent can be stopped. For a resource
to be considered in good health, all of its children must be in good health.
A service is considered failed if any of its resources fail. In this case, the expected course of action
is to restart the entire service, including the failed resource and the other resources that did not fail.
In a P6000 Cluster Extension environment, configure the P6000 Cluster Extension resource as the
parent resource in the service so that P6000 Cluster Extension can control the service behavior based
on the user configuration and storage device status. This means that the P6000 Cluster Extension
resource must be configured at the highest level in the dependency hierarchy.
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. P6000
Cluster Extension does not monitor the disk access status.
Storage system configurations
Cluster configurations typically consist of two or more server systems connected to a shared storage
system. P6000 Cluster Extension allows the dispersion of data center resources by enabling cluster
systems to take advantage of P6000/EVA storage systems configured for P6000 Continuous Access
operations. P6000 Cluster Extension connects the P6000 management software used to control
P6000/EVA storage systems (and P6000 Continuous Access) with the cluster software and uses the
cluster software to react to system hardware and application failures.
P6000 Cluster Extension behavior is based on four major considerations:
• Cluster software failover behaviors
• P6000 Cluster Extension user settings
• The replication mode setting for P6000 Continuous Access, which is used to configure the remote
replication feature of a P6000/EVA storage system environment based on your needs for applic-
ation service availability, data concurrency, and replication performance
• DR group member status information
P6000 Cluster Extension supports one-to-one and consolidated DR site configurations.
P6000 Cluster Extension features16