San-Based Mirroring Failure Types And Responses - Novell BUSINESS CONTINUITY CLUSTERING 1.0 - ADMINISTRATION Manual

2.11.1 San-based Mirroring Failure Types and Responses

Primary Cluster Fails but Primary SAN Does Not
This type of failure can be temporary (transient) or long-term. There should be an initial response
and then a long term response based on whether the failure is transient or long term. The initial
response is to restore the cluster to normal operations. The long-term response is total recovery from
the failure.
Promote the secondary LUN to primary. Cluster resources load (and become primary on the second
cluster). If the former primary SAN has not been demoted to secondary, you might need to demote it
manually. The former primary SAN must be demoted to secondary before bringing cluster servers
back up. Consult your SAN hardware documentation for instructions on demoting and promoting
SANs. You can use the cluster resetresources console command to change resource
states to offline and secondary. See the cluster resetresources command.
Prior to bringing up the cluster servers, the administrator must ensure the SAN is in a state in which
the cluster resources cannot come online and cause a divergence in data. Divergence in data occurs
when connectivity between SANS has been lost and both clusters assert they have ownership of
their respective disks.
Primary Cluster and Primary SAN Both Fail
Bring the primary SAN back up and follow your SAN vendor's instructions to remirror and, if
necessary, promote the former primary SAN back to primary. Then bring up the former primary
cluster servers and fail back the cluster resources.
Secondary Cluster Fails but Secondary SAN Does Not
No additional response is necessary for this failure other than recovering the secondary cluster.
When you bring the secondary cluster back up, the LUNs will still be in a secondary state to the
primary SAN.
Secondary Cluster and Secondary SAN Both Fail
Bring the secondary SAN back up and follow your SAN vendor's instructions to remirror. When you
bring the secondary cluster back up, the LUNs will still be in a secondary state to the primary SAN.
Primary SAN Fails but Primary Cluster Does Not
When the primary SAN fails, the primary cluster will also fail. Bring the primary SAN back up and
follow your SAN vendor's instructions to remirror and, if necessary promote the former primary
SAN back to primary. You might need to demote the LUNs and resources to secondary on the
primary SAN before bringing them back up. You can use the cluster resetresources
console command to change resource states to offline and secondary. See the cluster resetresources
command. Bring up the former primary cluster servers and failback resources.
Secondary SAN Fails but Secondary Cluster Does Not
When the secondary SAN fails, the secondary cluster will also fail. Bring the secondary SAN back
up and follow your SAN vendor's instructions to remirror. Then bring the secondary cluster back up.
When you bring the secondary SAN and cluster back up, resources will still be in a secondary state.
44 Novell Business Continuity Cluster Services 1.0 Administration Guide