Oracle B32100-01 - Manual (Page 186)

OracleAS Disaster Recovery: Introduction
10-2 Oracle Application Server Installation Guide
middle tiers. In an asymmetric topology, the number of instances required on the
standby site are fewer than the number on the production site and the number of
instances required on the standby site must be the minimum set of instances required
to run your site in the event of a switchover or failover operation.
As a small variation to this environment, you can set up the OracleAS Infrastructure
on the production site in an OracleAS Cold Failover Cluster environment. See
Section 10.2.4, "If You Want to Use OracleAS Cold Failover Cluster on the Production
Site"
for details.
For these supported topologies, OracleAS Guard will be installed in every Oracle
home on every system that is part of your production and standby topology
configured for the OracleAS Disaster Recovery solution.
OracleAS Guard can be installed as a standalone install kit located on OracleAS
Companion CD #2. See
Section 10.4, "Installing the OracleAS 10g (10.1.2.0.2)
Standalone Install of OracleAS Guard into Oracle Homes" for more information about
when this standalone kit should be installed.
Figure 10–1 shows an example symmetric OracleAS Disaster Recovery environment.
Each site has two nodes running middle tiers and a node running OracleAS
Infrastructure.
Data Synchronization
For OracleAS Disaster Recovery to work, data between the production and standby
sites must be synchronized so that failover can happen very quickly. Configuration
changes done at the production site must be synchronized with the standby site.
You need to synchronize two types of data. The synchronization method depends on
the type of data:
■
Use Oracle Data Guard to synchronize data in the OracleAS Metadata Repository
databases on the production and standby sites. You can configure Oracle Data
Guard to perform the synchronization.
■
Use the backup and recovery scripts to synchronize data outside of the database
(such as data stored in configuration files).
See the Oracle Application Server High Availability Guide for details on how to use Oracle
Data Guard and the backup and recovery scripts.