Designing Disaster Recovery Clusters using Metroclusters and Continentalclusters, Reprinted October 2011 (5900-1881)

At this point, you have completed configuring SADTA in the 3DC solution with the RAC database.
It is recommended that you verify the setup during the planned downtime for maintenance using
the procedure mentioned in “Verifying the Three Data Center Environment” (page 461).
Verifying the Three Data Center Environment
To verify the setup:
• Preview the data replication storage failover by using the cmdrprev command.
• Test the application startup at the recovery cluster.
• Test Continentalclusters recovery using the cmrecovercl command in the recovery
cluster.
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 32 (page 462) describes the exit values of the command.
Verifying the Three Data Center Environment 461