HP Serviceguard Toolkits for Database Replication Solutions manual RAC environment

Figure 7 RAC environment

In an RAC environment, Figure 7 (page 14), all the three packages (Primary, Data Receiver and Recovery Packages) are configured as Multi-Node packages (MNPs).

When the primary cluster is down, the recovery package on the recovery cluster must be brought up by manually running the cmrecovercl command. This command halts the Data Receiver package, which in turn halts the standby database. It then runs the recovery package, which brings up the database as a primary database by doing a role failover. In an RAC environment, the start up time of recovery package is more than that in a single-instance environment, since the role transition is differently performed. In an RAC environment, during role failover only one of the standby database instances (say, Instance A) should be running while others should be shutdown. These other instances wait for Instance A to perform role failover, shutdown, and then restart. Once these operations are performed on Instance A, the other instances are started. Hence start_script_timeout parameter in the package configuration should be appropriately specified.

Restoring the cluster in a Continentalclusters to its original state is a manual process. The following steps must be performed to restore the clusters to their original state:

1.Halt the recovery package — halts the recovery package

2.Resync primary database from the standby database.

3.Start the primary package— brings up the database on primary cluster as a primary database

4.Start the Data Receiver package— brings up the database on the recovery cluster as a standby database

NOTE: In an RAC environment, the FAST_START_FAILOVER feature of ODG Broker must not be enabled when using the ODG toolkit in Continentalclusters environment. When the ODG Broker feature Fast Start Failover is enabled, it automatically changes the role of one of the available standby database to “primary” role, if there is a disaster at the primary database site. Also, the toolkit that performs role transitions in Continentalclusters environment might select a different standby database for role change. This might lead to data integrity issues. Hence, FAST START FAILOVER feature must be disabled in Continentalclusters environment.

Metrocluster and extended distance cluster environments

Metrocluster is an HP high availability product for Serviceguard customers who require integrated disaster recovery solutions. HP Metrocluster uses Serviceguard clustering technology to form a single cluster of systems that are located apart from each other at different data centers at metropolitan distances.

14 Serviceguard toolkit for Oracle Data Guard