Forcing a Takeover on a System That Uses SRDF Data Replication

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Perform a takeover when applications need to be brought online on the secondary cluster regardless of whether the data is completely consistent between the primary volume and the secondary volume. The information in this section assumes that the protection group has been started.

The following steps occur after a takeover is initiated:

If the former primary cluster, cluster-paris, can be reached and the protection group is not locked for notification handling or some other reason, the application services are taken offline on the former primary cluster.

For a reminder of which cluster is cluster-paris, see Example Geographic Edition Cluster Configuration in Oracle Solaris Cluster Geographic Edition System Administration Guide .
Data volumes of the former primary cluster, cluster-paris, are taken over by the new primary cluster, cluster-newyork.

Note - This data might be inconsistent with the original primary volumes. After the takeover, data replication from the new primary cluster, cluster-newyork, to the former primary cluster, cluster-paris, is stopped.
Application services are brought online on the new primary cluster, cluster-newyork.

For more details about takeover and the effects of the geopg takeover command, see Appendix C, Disaster Recovery Administration Example, in Oracle Solaris Cluster Geographic Edition System Administration Guide .

For details about the possible conditions of the primary and secondary cluster before and after takeover, see Appendix D, Takeover Postconditions, in Oracle Solaris Cluster Geographic Edition System Administration Guide .

The following sections describe the steps you must perform to force a takeover by a secondary cluster.

Validations That Occur Before a Takeover

When a takeover is initiated by using the geopg takeover command, the data replication subsystem runs several validations on both clusters. These step are conducted on the original primary cluster only if the primary cluster can be reached. If validation on the original primary cluster fails, the takeover still occurs.

First, the replication subsystem checks that the SRDF device group is in a valid aggregate RDF pair state. The SRDF commands that are used for the takeover are described in the following table.

Table 7 SRDF Takeover Validations on the New Primary Cluster

Aggregate RDF Pair State	Protection Group Local Role	SRDF Takeover Commands That Are Run on `cluster-newyork`
`FailedOver`	Primary	`symrdf $option $dg write_disable r2` `symrdf -g dg suspend` `symrdf $option $dg rw_enable r1`
`FailedOver`	Secondary	No command is run.
`Synchronized`, `Suspended`, `R1 Updated`, `Partitioned`	All	`symrdf -g dg failover`

Results of a Takeover From a Replication Perspective

From a replication perspective, after a successful takeover, the Local-role property of the protection group is changed to reflect the new role, regardless of whether the application could be brought online on the new primary cluster as part of the takeover operation. On cluster-newyork, where the protection group had a Local-role of Secondary, the Local-role property of the protection group becomes Primary. On cluster-paris, where the protection group had a Local-role of Primary, the following might occur:

If the cluster can be reached, the Local-role property of the protection group becomes Secondary.
If the cluster cannot be reached, the Local-role property of the protection group remains Primary.

If the takeover is successful, the applications are brought online. You do not need to run a separate geopg start command.

Caution - After a successful takeover, data replication between the new primary cluster, cluster-newyork, and the old primary cluster, cluster-paris, is stopped. If you want to run a geopg start command, you must use the –n option to prevent replication from resuming.