HP Serviceguard Oracle DataGuard Toolkit User Guide, April 2011

Figure 8 Single-instance Data Guard configuration in Metrocluster with standby database residing
outside Metrocluster
NOTE: This configuration is supported both in single-instance and RAC environments. For better
understanding, the packages in the Figure 8 (page 15) are shown for a single-instance database.
In Figure 8 (page 15), Metrocluster is configured with two data centers; one as the primary site,
and the other as the recovery site. The Data Guard primary database instance is configured in
Data Center 1 such that the archived logs and the primary database reside on the disk that is
shared locally between the nodes in that data center. The primary database instance will be brought
up on any one node in Data Center 1, while other nodes in the data center will serve as backup
nodes for that instance. Array-based replication technology enables the data written to the storage
array in Data Center 1, to be replicated to the storage array located in Data Center 2. It is not
necessary to configure the standby database in Data Center 2 as the data replication is taken care
of by the Metrocluster solution.
The standby database instance is configured at a third location (say site 3), which is not configured
within the Metrocluster environment. The third location is a separate Serviceguard cluster with two
nodes and a shared disk. The standby database instance will be brought up on any one node in
the third location, and the database and the archived logs will be located on the shared disk. If
high availability is not needed for the standby database then the third location need not be
configured in a Serviceguard cluster. In such a situation, there will be only one server at the third
location and the standby database instance will need to be brought up manually.
It is recommended not to configure the Standby database in the same Metrocluster as the Primary
database. This is because, a Metrocluster with two data centers in which the Primary database
package is running on the first site replicates (hardware replication from array to array) to the
second site. Configuring the standby database on the second site of the Metrocluster, hence, makes
it a redundant configuration.
In case of a disaster, if Data Center 1 is down, the primary database instance will be failed over
to Data Center 2 and will continue to function as a primary database. Since Metrocluster has
achieved data replication from Data Center 1 to 2, there will not be any problems when starting
the primary database at Data Center 2 using the replicated data from the shared disk. Once the
Supported configurations 15