Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access for P9000 and XP A.11.00
Previewing the Data Replication Storage Failover by Using cmdrprev
To preview the data replication storage failover and to identify potential problems that can cause
Metrocluster package failover or Continentalclusters recovery to fail, run the following command
on all nodes in the 3DC solution:
# cmdrprev {[–p <package_name>] | [-e <Metrocluster_environment_file>]
The cmdrprev command previews the failover of the data replication storage that indicates if the
storage preparation will be successful or not in event of an actual package failover.
The storage failover can fail due to many reasons and can be categorized as the following:
• Incorrect configuration or setup of 3DC environment
Invalid RAID Manager configuration file◦
◦ The command device is not functional
◦ The installed Metrocluster binaries are corrupt
◦ Incorrect file permissions
• Invalid data replication state
The data may not be in the write-order, which can be due to a track copy at the time of
the failover attempt.
◦
◦ The data is not current (lagging behind the primary) and the 3DC parameters configured
in the package are not set correctly to allow a failover on non-current data.
The command parses the Metrocluster Environment file associated to the <package name> or
which is provided as the input parameter <Metrocluster env file>with the -e option. It ensures proper
syntax, and verifies for valid parameter values. The cmdrprev command previews the data
replication preparation steps based on the values in the Metrocluster environment file and the
current state of replication. This command displays a detailed log of all the preparation steps and
the changes to the data replication environment that would have been done in case of an actual
preparation. The command does not change the data replication environment and can be used
even if the package associated with the data replication storage is up on the cluster.
NOTE: Detailed messages from the preview process are logged into stdout.
The command exit value indicates if the storage failover in an actual package will succeed or not.
Table 11 (page 140) describes the exit values of the command.
Table 11 Command Exit Value and its Description
DescriptionValue
The data replication storage failover preview command failed, due to invalid command usage or
due to invalid input parameters.
—1
The data replication storage failover preview is successful from a specific node. This indicates if
data replication storage failover will be successful in the event of the package failing over to this
node.
0
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 from any node in the cluster.
1
The data replication storage failover preview failed due to node specific error conditions or due to
transient conditions. This indicates that in the event of an actual recovery process, the data replication
2
storage failover will not succeed on that node. Failover may be successful if attempted at a later
time or attempted on a different node in the cluster.
140 Designing a Three Data Center Disaster Recovery Solution