Forcing a Takeover on a System That Uses EMC Symmetrix Remote Data Facility Data Replication

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 Sun Cluster Geographic Edition Cluster Configuration in Sun 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.

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  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.

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• 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 Overview of Disaster Recovery Administration in Sun Cluster Geographic Edition System Administration Guide.

For details about the possible conditions of the primary and secondary cluster before and after takeover, see Appendix C, Takeover Postconditions, in Sun 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

• Results of a Takeover From a Replication Perspective

• How to Force Immediate Takeover of EMC Symmetrix Remote Data Facility Services 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 EMC Symmetrix Remote Data Facility device group is in a valid aggregate RDF pair state. The EMC Symmetrix Remote Data Facility commands that are used for the takeover are described in the following table.

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.

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.

How to Force Immediate Takeover of EMC Symmetrix Remote Data Facility Services by a Secondary Cluster

Before You Begin

Before you force the secondary cluster to assume the activity of the primary cluster, ensure that the following conditions are met:

• Sun Cluster Geographic Edition software is up and running on the cluster.

• The cluster is a member of a partnership.

• The Configuration status of the protection group is OK on the secondary cluster.

1. Log in to a node in the secondary cluster.

   You must be assigned the Geo Management RBAC rights profile to complete this procedure. For more information about RBAC, see Sun Cluster Geographic Edition Software and RBAC in Sun Cluster Geographic Edition System Administration Guide.

2. Initiate the takeover.

   # geopg takeover [-f] protectiongroupname

   -f

   Forces the command to perform the operation without your confirmation

   protectiongroupname

   Specifies the name of the protection group

Example 3–2 Forcing a Takeover by a Secondary Cluster

This example forces the takeover of srdfpg by the secondary cluster cluster-newyork.

The phys-newyork-1 cluster is the first node of the secondary cluster. For a reminder of which node is phys-newyork-1, see Example Sun Cluster Geographic Edition Cluster Configuration in Sun Cluster Geographic Edition System Administration Guide.

phys-newyork-1# geopg takeover -f srdfpg

Next Steps

For information about the state of the primary and secondary clusters after a takeover, see Appendix C, Takeover Postconditions, in Sun Cluster Geographic Edition System Administration Guide.