Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access for P9000 and XP A.11.00

Because, a disaster tolerant RAC database has two identical but independent RAC databases
configured over the replicated storage in a Metrocluster, it is important to prevent packages of
both sites RAC MNP stacks to be up and running simultaneously. If the packages of the redundant
stack at both sites are running simultaneously, it leads to data corruption. SADTA provides a Site
Safety Latch mechanism at the site nodes that prevents inadvertent simultaneous direct startup of
the RAC MNP stack packages at both sites.
Multiple site aware disaster tolerant RAC databases can be configured in a Metrocluster. Figure 48
shows one such configuration with two site aware disaster tolerant RAC databases: hrdb and
salesdb.
Figure 48 Sample configuration
SITE A_HR_MNP
Site safety
latch
Site safety
latch
SITE A_HR_DG/MP MNP
SITE A CRS
SITE A_SALES_DG/MP MNP
SITE A_SALES RAC_MNP
SITE A CFS
Site A
Node 1 Node 2
SG CFS SMNP
Node 3 Node 4
Site B
SITE B_HR_MNP
SITE B_HR_DG/MP MNP
SITE B CRS
SITE B_SALES_DG/MP MNP
SITE B_SALES RAC_MNP
SITE B CFS
Active Inactive Active Inactive
Multiple RAC databases can be configured using a separate Site Controller Package infrastructure
for every RAC database. every RAC database must have its own Site Controller Package, Site
Safety Latch, RAC MNP package stack, and replication disk group in the Metrocluster. The
site-specific Oracle Clusterware and CFS sub-clusters are common resources for all RAC databases.
To add another RAC database to an existing Metrocluster, two replicas of the RAC database and
the RAC MNP stack packages on both sites, in a separate Site Controller Package, must be
configured.
Because the SADTA configuration requires two replicas of the RAC database configuration, the
Oracle Network and Services must be configured accordingly for the disaster tolerant database
clients to automatically reconnect to the new active site after a site failover is complete. For more
information about configuring access for Oracle RAC database, see “Configuring client access
for Oracle database 10gR2 RAC” (page 208).
Configuring Oracle RAC database in a Site Aware Disaster Tolerant
Architecture(SADTA)
This section describes how to configure Oracle RAC database in a SADTA. The subsequent sections
elaborate on the configuration procedures using Oracle Database 10gR2 RAC as an example.
190 Configuring Oracle RAC in SADTA