HP Serviceguard Oracle DataGuard Toolkit User Guide, April 2011

primary database instance comes up at Data Center 2, it will continue to send the archived logs
to the standby database located at the third location.
A configuration in which another Primary instance of Oracle is running at the second site, and
replicates to a third location is also possible.
Figure 9 Data Guard setup in an EDC environment
HP Serviceguard Extended Distance Cluster (EDC) is a special configuration of an HP Serviceguard
cluster that allows the cluster to span across two separate data centers for increased availability
and protection against an outage that might affect one of the data centers. HP Serviceguard EDC
provides automatic or manual failover capabilities for mission-critical data and applications in
data centers up to 100 kilometers apart. It protects geographically dispersed data centers from
unplanned downtime caused by system and application failures, operator errors and local disasters.
In addition, it enhances data and application availability.
Figure 9 (page 16), shows a Data Guard setup in an EDC environment. All the four nodes are
present inside the same Serviceguard cluster. Primary database is configured at Site A and Standby
database is configured at site B. Primary package can failover in Site A but should not be configured
to failover to Site B. Similarly, Standby database can failover inside Site B but should not be
configured to failover to Site A.
When Site A goes down, the role of Standby on Site B has to be manually changed to primary,
since the role transitions are not be supported in this configuration.
16 Serviceguard support for Oracle Data Guard