Installation and Setup
55
2.6.1 SAN-Based Mirroring Failure Types and Responses
SAN-based mirroring failure types and responses are described in the following sections:
“Primary Cluster Fails but Primary SAN Does Not” on page 55
“Primary Cluster and Primary SAN Both Fail” on page 55
“Secondary Cluster Fails but Secondary SAN Does Not” on page 55
“Secondary Cluster and Secondary SAN Both Fail” on page 55
“Primary SAN Fails but Primary Cluster Does Not” on page 56
“Secondary SAN Fails but Secondary Cluster Does Not” on page 56
“Intersite SAN Connectivity Is Lost” on page 56
“Intersite LAN Connectivity Is Lost” on page 56
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.
Prior to bringing up the cluster servers, you must ensure that 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 that 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 are still 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 are still in a secondary state to the primary SAN.
Summary of Contents for BUSINESS CONTINUITY CLUSTERING 1.1 SP1
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