Actions Performed by the Geographic Edition Framework During a Takeover

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A takeover consists of the following actions:

If the former primary cluster can be reached and the protection group is not locked for notification handling or some other reason, the protection group is deactivated.
The data of the former primary cluster is taken over by the new primary cluster.

Note - The data on the former primary cluster might not be consistent with the data on the original primary cluster. Data replication from the new primary cluster to the former primary cluster is stopped.
Application services are brought online on the new primary cluster.
The protection group is activated without replication enabled.

For Hitachi TrueCopy or Universal Replicator, when a takeover is initiated by using the geopg takeover command, the data replication subsystem runs several validations on both clusters. These steps 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 Hitachi TrueCopy or Universal Replicator device group is in a valid aggregate device group state. Then, the replication subsystem checks that the local device group states on the target primary cluster, cluster-newyork, are not 32 or 52. These values correspond to a SVOL_COPY state, for which the horctakeover command fails.

Tip - Order-of-writes on SVOL are not maintained during the Hitachi TrueCopy or Universal Replicator COPY state. In a situation where SVOL has some out-of-order writes, if the user attempts to bring ZFS online, the import might fail. Creating backups provides protection if the primary goes down while in the COPY state. The administrator can use the backup to update the SVOL and then issue the geopg takeover to bring the configuration online on the secondary cluster.

The Hitachi TrueCopy or Universal Replicator commands that are used for the takeover are described in the following table.

Table 6 Hitachi TrueCopy and Universal Replicator Takeover Validations on the New Primary Cluster

Aggregate Device Group State	Valid Local State Device Group State	Hitachi TrueCopy and Universal Replicator Takeover Commands That Are Run on `cluster-newyork`
SMPL	All	No command is run.
Regular primary	All	No command is run.
Regular secondary	All Regular secondary states except `32` or `52` For a list of Regular secondary states, refer to How the State of the Hitachi TrueCopy or Universal Replicator Data Replication Component Is Validated in Oracle Solaris Cluster Geographic Edition Data Replication Guide for Hitachi TrueCopy and Universal Replicator.	`horctakeover –S –g dg [–t]` The`–t` option is given when the `fence_level` of the Hitachi TrueCopy or Universal Replicator device group is `async`. The value is calculated as 80% of the `Timeout` property of the protection group. For example, if the protection group has a `Timeout` of 200 seconds, the value of `–t` used in this command will be 80% of 200 seconds, or 160 seconds.
Takeover primary	All	No command is run.
Takeover secondary	All	`pairsplit –R –g dg` `pairsplit –S –g dg`

For more details about takeover and the effects of the geopg takeover command, see Appendix B, Disaster Recovery Administration Example, in Oracle Solaris Cluster 4.3 Geographic Edition System Administration Guide.

For details about the possible conditions of the primary and secondary cluster before and after a takeover, see Appendix C, Post-Takeover Conditions, in Oracle Solaris Cluster 4.3 Geographic Edition System Administration Guide.