Building Disaster Recovery Serviceguard Solutions Using Metrocluster with EMC SRDF

A disaster tolerant RAC database has two identical but independent RAC databases configured
over the replicated storage in a Metrocluster. Therefore, packages of both sites RAC MNP stacks
must not 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 23
shows one such configuration with two site aware disaster tolerant RAC databases: hrdb and
salesdb.
Figure 23 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 each RAC database. Each 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, configure two replicas of the RAC
database and the RAC MNP stack packages on both sites, and manage them using a separate
Site Controller Package.
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 117).
Configuring Oracle RAC database in a SADTA
This section describes the procedure to configure Oracle RAC database in a SADTA. The subsequent
sections describe the configuration procedures using Oracle Database 10gR2 RAC as an example.
Setting up SADTA
This section summarizes the procedures required to configure Oracle RAC database in a SADTA.
Configuring Oracle RAC database in a SADTA 99