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

quorum depends on the defined no-quorum policy. This behavior is in effect until the cluster is fenced.
When the cluster is fenced, the resources owned by the fenced nodes fail over to active cluster nodes.
STONITH
STONITH is an SLE HA cluster fencing method. SLE HA cluster provides STONITH plug-ins for devices
such as UPS, PDU, Blade power control devices, and lights out devices. Some plug-ins can STONITH
more than one node (for example, Split Brain Detector STONITH) and some can STONITH only one
node (for example, HP iLO STONITH).
HP iLO STONITH uses the power control functions of an HP iLO device to STONITH a node that has
lost quorum and needs to be fenced.
IMPORTANT:
If all of the iLO devices in a cluster are connected using a single network, a single switch failure might
disable iLO, preventing nodes from being fenced. This failure might be difficult to detect, especially
before a node failure where iLO features would be required.
The STONITH action can be set to power off or reset, depending on the environment requirements.
• Power off: The STONITH agent powers off the nodes in the errant subcluster.
• Reset: The STONITH agent resets the nodes in the errant subcluster, and the nodes try to automat-
ically rejoin the cluster.
NOTE:
IPMI fencing can be used for Integrity servers that do not support RIBCL scripting.
Networking in an SLE HA cluster
Configuring redundant and independent cluster communication paths is a good way to avoid Split
Brain conditions. With redundancy in communication paths, the loss of a single interface or switch
does not break the communication between nodes and prevents Split Brain conditions.
Administrators can configure multiple independent communication paths. HP recommends using
bonded Ethernet channels.
Resource constraints
Resource constraints allow administrators to specify which cluster nodes resources can run on, the
order resources are loaded, and the other resources a specific resource is dependent on.
There are three types of resource constraints:
• Resource location: Defines the nodes on which a resource can run, cannot run, or is preferred to
be run.
• Resource colocation: Defines which resources can or cannot run together on a node.
• Resource order: Defines the sequence of actions for resources running on a node.
Resource operation attribute
SLE HA does not monitor resource health by default. To enable this feature, add the monitor operation
to the resource definition. You can specify the interval attribute and the timeout attribute for a monitor
XP Cluster Extension features16