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Using MSCS 69
The Cluster Service continues to try and fail over a group until it succeeds or until the number
of attempts occurs within a predetermined time span. A group’s failover policy specifies the
maximum number of failover attempts that can occur in an interval of time. The Cluster
Service will discontinue the failover process when it exceeds the number of attempts in the
group’s failover policy.
Modifying Your Failover Policy
Because a group’s failover policy provides a framework for the failover process, make sure that
your failover policy is appropriate for your particular needs. When you modify your failover
policy, consider the following guidelines:
• Define the method in which the Cluster Service detects and responds to individual resource
failures in a group.
• Establish dependency relationships between the cluster resources to control the order in
which the Cluster Service takes resources offline.
•Specify
Time-out
, failover
Threshold
, and failover
Period
for your cluster resources.
–
Time-out
controls how long the Cluster Service waits for the resource to shut down.
–
Threshold
and
Period
control how many times the Cluster Service attempts to fail over a
resource in a particular period of time.
• Specify a
Possible owner list
for your cluster resources. The
Possible owner list
for a resource
controls which cluster nodes are allowed to host the resource.
Failback
When the System Administrator repairs and restarts the failed cluster node, the opposite
process occurs. After the original cluster node has been restarted and rejoins the cluster, the
Cluster Service will bring the running application and its resources offline, move them from the
failover cluster node to the original cluster node, and then restart the application. This process
of returning the resources back to their original cluster node is called failback.
You can configure failback to occur immediately at any given time, or not at all. However, be
sure to configure the failback time during your offpeak hours to minimize the effect on users, as
they may see a delay in service until the resources come back online.
se500wbk1.book Page 69 Thursday, June 16, 2005 4:19 PM