Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access XP P9000 for Linux B.01.00.00

3 Metrocluster features
Data replication storage failover preview
In an actual failure, packages are failed over to the standby site. As part of the package startup,
the underlying storage is failed over based on the parameters defined in the package configuration.
The storage failover can fail due to many reasons, and can be categorized as the following:
• Incorrect configuration or setup of Metrocluster and data replication environment.
The storage failover can fail if the installed Metrocluster binaries are corrupt or have incorrect
file permissions or invalid horcm configuration file or the command device is not functional.
• Invalid data replication state
The data might not be in write-order due to a track copy at the time of the failover attempt.
Also, the data is not current (lagging behind the primary) and the Metrocluster parameter are
not set correctly to allow a failover on non-current data.
The command cmdrprev previews the failover of data replication storage. It determines if storage
failover is successful during an actual package failover. This command can be used in both
Metrocluster and Continentalclusters. If the preview fails, the cmdrprev command displays a
detailed log that lists the cause for failure in stdout. The command options are as follows:
cmdrprev -p <package_name>
See cmdrprev manpage for further reference.
The command exit value indicates if the storage failover in an actual package will succeed or not.
Table 4 describes the exit values of the command.
Table 4 Command exit value and its description
DescriptionValue
The data replication storage failover preview failed. This indicates that in the event of an
actual recovery process, the data replication storage failover will not succeed on any node
in the cluster.
-1
The failure is due to invalid command usage or due to invalid input parameters.
The data replication storage failover preview is successful on the node where the command
is run.
0
This indicates if data replication storage failover is successful in the event of a package
failover.
The data replication storage failover preview failed.1
This indicates that in the event of an actual recovery process, the data replication storage
failover will not succeed on any node in the cluster.
The data replication storage failover preview failed due to node specific error conditions or
due to transient conditions.
2
This indicates that in the event of an actual recovery process, the data replication storage
failover will not succeed on that node. Failover might be successful if attempted at a later time
or attempted on a different node in the cluster.
Rolling upgrade for Metrocluster
Rolling Upgrade allows you to upgrade the software components of the cluster with minimal
downtime to the applications managed by Metrocluster. See Rolling upgrade for the procedure.
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