martes, 22 de septiembre de 2009

RMAN Creating a High-Availability Recovery Catalog

Creating a High-Availability Recovery Catalog
You have registered a large number of databases in a single recovery catalog and want to
ensure that the recovery catalog is always available to perform backup and recovery tasks.
That is, you want a high-availability solution for the RMAN recovery catalog.
The solution is to maintain multiple, redundant recovery catalogs. If you’re using the recovery
catalog to manage the backup and recovery tasks for a large number of production databases,
maintaining high availability becomes critical. You can ensure high availability of the recovery
catalog just as you would any other Oracle database—by using a standby recovery catalog
instance. In the case of recovery catalogs, however, you really don’t use a special standby database
for the alternate recovery catalog instance—you simply maintain a secondary recovery
catalog that can take over from the primary recovery catalog in the event disaster strikes.

Here’s a simple outline of the strategy for using a standby recovery catalog:
1. Create a secondary recovery catalog in a separate Oracle database.
2. Register all databases—all that you have registered in your primary catalog—in the
secondary recovery catalog.
3. The primary recovery catalog is synchronized automatically during the normal backups
of the target databases.
4. Synchronize the secondary recovery catalog manually with the resync catalog command
after connecting to each of the target databases registered in the catalog.
5. Switch to the secondary catalog as the primary recovery catalog when necessary after
resynchronizing it first. Switching to the secondary catalog is as easy as can be. Simply
connect to that catalog instead of to the primary one. The secondary catalog will be
now your primary catalog.
How It Works
It’s important to synchronize the secondary recovery catalog manually on a frequent basis so
the catalog remains current. This way, when you are forced to fall back on the secondary catalog,
it’ll have all the backup metadata you need.
You must back up the secondary recovery catalog database just as you would the primary
catalog database to provide high availability.