Application Server Guard, Disaster Recovery for Oracle Application Server
Application Server Guard is Next level of Disaster Recovery Solution by Oracle (Currently only for Application Server/ Fusion Middleware). Application Server Guard (with underlying dataguard for database) incorporate Middle Tier configuration recovery on standby site.
Lets discover overview & main component of AS Guard ( ASG , also called as DSA Distributed Server Architecture).
Components of AS Guard
Application Server Guard also called as AS Guard is automatically Installed with 10g Application Server . Real features/advantages of AS Guard started with version 10.1.2.0.2 and bugs associated in this release with some more features are fixed in Version 10.1.2.2.0 . AS Guard binaries are Installed under folder “DSA” under oracle_home . If you have standalone database , you can install standalone AS Guard under database oracle_home. Software is available at Here, Click here to download
AS Guard consist of Server & client (any ASGuard with asgctl.sh can act as Client).
For database it uses dataguard (You don’t have to configured dataguard for database AS Guard will configure it for you if your database was part of Application Server Installation) If your database is created by MRCA/Repca (Metadata Repository Creation Assistance Tool) then you have to configure Dataguard at your own.
For Identity Management & Middle tier configuration it uses backup & recovery tool in Application Server (This is automated by AS Guard, you don’t have to do anything)
Primary & Standby Site
Primary & Standby site can be synchronous (Same number of nodes in standby as primary) or asynchronous (Number of nodes in standby are less as compared to primary-Like primary site is with two middle tier and one infra tier where as standby site with only one middle tier & one infra tier- P.S. standby site should have at least one middle tier & one infrastructure tier)
Start/Stop AS Guard Server
If AS Guard Server is part of application Server you start it using opmnctl like
opmnctl startproc ias-component=DSA
For standalone AS Guard you use dsaServer.sh under oracle_home/dsa/bin like
nohup dsaServer.sh &
Operations in AS Guard
Instantiate –
This is process of building primary & standby relationship and done only once. In this step AS Guard will create standby database for Application Server metadata repository database , backup configuration files from primary site & restore them to standby site
Sync-
This is method of synching standby site with primary site. In this step standby database is synched with primary database . Configuration files from IM node & middle tier node on primary site are backed up & restored in standby site
Switchover-
This is the process of converting role of primary in to standby & standby into primary. Useful in situation like server maintenance in primary site or any activity on primary site so that standby site can be used as primary site
Failover-
This is the process of converting standby site as primary (same as above except here primary site is not converted as standby). Useful in situation if primary site is not available because of some reason.
For using AS Guard (Application Server Guard) as Disaster Recovery solution , you have to select HA (High Availability) & then Virtual Host during IM Installation.
More on AS Guard configuration coming soon….