Application Server Guard
Oracle Application Server (OAS) Guard is a technology that keeps the OAS configuration data synchronized between production and standby sites. Planned outages of the production site can be performed without interruption of service by switching over to the standby site. Unplanned outages are managed by failing over to the standby site using an OAS Guard fail-over operation.
Full OAS Enterprise Edition licenses are required for both the active and standby application servers systems.
The AS Guard binaries are installed in directory "DSA" (Distributed Server Architecture) under the ORACLE_HOME directory.
Oracle Data Guard is used to protect the Infrastructure databases.
You don't have to configure Data Guard for Infrastructure databases that was installed as part of the Application Server installation as AS Guard will do it for you. However, if you've created your Infrastructure databases with REPCA, you need to setup Data Guard on your own.
 Identity Management & Middle Tier
AS Guard will automatically backup and restore configuration files with the Application Server Backup/Recovery tool.
 Start/ Stop
To start the server component (on all primary and secondary servers):
opmnctl startproc ias-component=DSA
To start the client utility, execute ASGCTL in ORACLE_HOME/dsa/bin:
$ asgctl.sh Application Server Guard: Release 10.1.2.0.2 (c) Copyright 2004, 2005 Oracle Corporation. All rights reserved. ASGCTL> HELP
 AS Guard Operations
- Discover topology
ASGCTL> connect asg infra ias_admin/infra123 Successfully connected to infraha:7890 ASGCTL> discover topology oidpasswd=infra123 ASGCTL> verify topology ...
- Instantiate - initial setup
- AS Guard will even put the infrastructure DB into arclog mode, copy it to the secondary and establish the data guard standby.
- Sync - Force a sync (by default this will happen automatically)
- Switchover - graceful role reversal between Primary and Secondary
- Failover - fail-over from primary to secondary site