Working with the Recovery Catalog
Using the recovery catalog is purely optional, as Oracle can use the control file to store the RMAN repository data (metadata). However, as explained earlier in this chapter, it's a good idea to spend the little time it takes to create and use the recovery catalog. I assume the use of the recovery catalog in the discussions in this and the next chapter.
| Tip |
Make sure that the database in which the recovery catalog is being created runs in archivelog mode. This ensures that you can always perform a PITR. |
To create the recovery catalog, you must first connect to the database in which you want to create the recovery catalog. You need to create a new recovery catalog owner schema (usually named rman), grant the necessary privileges to it, and then create the recovery catalog. Once you create the catalog, you can register databases in it.
Creating the Recovery Catalog Schema
In order to use the recovery catalog, you need to first create a recovery catalog schema. You can create this schema or user in an existing tablespace or in a new tablespace created for this purpose. The recovery catalog itself is stored in the default tablespace of this schema. The following example creates a schema called rman:
SQL> CREATE USER RMAN IDENTIFIED BY rman
TEMPORARY TABLESPACE temp
DEFAULT TABLESPACE rman_tbsp
QUOTA UNLIMITED ON rman_tbsp
User created.
SQL>
Make sure you first create the rman_tbsp tablespace for the user rman.
Making the Necessary Grants
The new rman schema owner, rman, needs privileges to maintain and query the recovery catalog. You do this by granting the user the RECOVERY_CATALOG_OWNER role. The following code shows how to make the necessary grants to user rman:
SQL> GRANT RECOVERY_CATALOG_OWNER TO rman; Grant succeeded. SQL>
Connecting to RMAN
You can connect to RMAN in one of two ways. One way is to first invoke RMAN, and then use the CONNECT CATALOG command to connect to it, as shown here (nicko is the database containing the recovery catalog in this example):
$ rman Recovery Manager: Release 11.1.0.6.0 - Production on Thu Mar 27 11:36:34 2008 Copyright (c) 1982, 2007, Oracle. All rights reserved. RMAN> CONNECT CATALOG rman/rman@nicko connected to recovery catalog database RMAN>
You can also connect directly from the operating system level, as follows:
$ rman CATALOG rman/rman@nicko connected to recovery catalog database RMAN>
When you connect to the catalog database directly, you still aren't connected to the target database (unless the target and the catalog database are the same). To connect to the target database, you must now use the following command from within the RMAN interface (nina is the target database name):
Instead of first connecting to the recovery catalog and then to the target database, you can use the following method to connect to the recovery catalog and to the target database in one step:
$ rman catalog rman/rman@nicko target nina Recovery Manager: Release 11.1.0.6.0 - Production on Thu Mar 27 11:36:34 2008 Copyright (c) 1982, 2007, Oracle. All rights reserved.target database password: connected to target database: NINA (DBID=1974138212) connected to recovery catalog database RMAN>
| Tip |
Although you can create the recovery catalog schema in the target database itself, Oracle recommends that you use a dedicated recovery catalog database, to secure the recovery catalog. This way, if the target database needs to be recovered, you'll have the necessary recovery data available in the recovery catalog. |
Creating the Recovery Catalog
If you want to utilize the recovery catalog (instead of the default method of using the control file) to store the RMAN metadata, you must first create it in the recovery catalog owner's (rman) schema.
First, connect to the catalog database in one of the two ways shown in the previous section. Next, use the CREATE CATALOG command, which will create the recovery catalog:
RMAN> CREATE CATALOG; recovery catalog created RMAN>
The CREATE CATALOG command creates the RMAN recovery catalog in the tablespace rman_tbsp, which you assigned as the default tablespace for the user rman.
The DROP CATALOG command will remove the recovery catalog:
RMAN> DROP CATALOG; Recovery catalog owner is RMAN Enter DROP CATALOG command again to confirm catalog removal RMAN> DROP CATALOG; Recovery catalog dropped RMAN>.
Registering a Database
For RMAN to do its job, you need to register the target database you want to back up and recover. Registration means that a database is enrolled in the recovery catalog. Once you register the database, RMAN will automatically get all the relevant metadata pertaining to the target database and store it in its own schema.
You don't need a separate recovery catalog for each of your Oracle databases; you can register all your databases in a single recovery catalog.
To register a new database in the recovery catalog, first connect to the target database:
$ rman catalog rman/rman@nicko target nina
Recovery Manager: Release 11.1.0.6.0 - Production on Thu Mar 27 11:36:34 2008
Copyright (c) 1982, 2007, Oracle. All rights reserved.
target database Password:
connected to target database: NINA (DBID=1974138212)
connected to recovery catalog database
RMAN>
| Caution |
Make sure you set the ORACLE_SID to the target database SID before you register a database in the recovery catalog. Otherwise, when you specify the target, you'll connect to the database whose instance name matches the ORACLE_SID of your UNIX session, not to the target database. |
Next, register the database in the recovery catalog:
RMAN> REGISTER DATABASE; database registered in recovery catalog starting full resync of recovery catalog full resync complete RMAN>
The target database is now successfully registered in the recovery catalog. At this point, you can use the REPORT SCHEMA command to make sure all the datafiles of the target database show up in the list.
You can also issue the following command to check the incarnation of the database:
RMAN> LIST INCARNATION; List of Database Incarnations DB Key Inc Key DB Name DB ID STATUS Reset SCN Reset Time ------- ------- -------- ----------- ---------- ---------- ----------- 1 8 NINA 1974138212 PARENT 1 11-JAN-08 1 2 NINA 1974138212 CURRENT 318842 05-JUN-08 RMAN>
Maintaining the Recovery Catalog
If you choose to create and use a recovery catalog, you must know how to maintain it. The following sections explain important recovery catalog maintenance tasks.
Resynchronizing the Recovery Catalog
Changes made to the target database structure aren't automatically propagated to the recovery catalog. The BACKUP and COPY commands automatically perform a resynchronization each time you perform a backup or copy. But you may need to manually resynchronize the recovery catalog under two circumstances: when your target database has just undergone a number of physical changes and when the target database is performing a very large number of log switches in between the backups.
During a resync operation, RMAN reads the target database's control file to update the information it keeps regarding datafiles, log switches, physical schema, and so forth. Oracle recommends that you resynchronize the recovery catalog after making any changes to the physical structure of a target database. You issue the RESYNC CATALOG command as follows, after connecting to the target database:
RMAN> RESYNC CATALOG; starting full resync of recovery catalog full resync complete RMAN>
Backing Up the Recovery Catalog
You should always back up the recovery catalog database immediately after you back up the target database. Backing up the recovery catalog becomes even more critical if you're using a single recovery catalog to store the metadata of all the databases in your system. You should follow these principles to afford the maximum possible security to the recovery catalog database:
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Back up the recovery catalog on a frequent basis.
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Never store the recovery catalog in the target database. You could end up losing the target database and the recovery catalog at the same time if there's a media failure.
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Always run the database holding the recovery catalog in archivelog mode.
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Make multiple copies of the recovery catalog database backup, preferably to tape, in addition to disk backups.
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Set the retention policy to a value greater than 1.
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Set CONTROLFILE AUTOBACKUP to ON, thus ensuring that you can always recover the recovery catalog database, provided you have the control file auto-backup on hand.
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Set a very high value for CONTROL_FILE_RECORD_KEEP_TIME, so the control file won't be over-written quickly, wiping out your RMAN repository data.
Note that in addition to using RMAN to back up the recovery catalog database, you can use the Data Pump Export utility to create logical backups of the recovery catalog database.
Recovering the Recovery Catalog
In order to restore and recover the recovery catalog database, you must first restore the control file and the server parameter file for the database from the auto-backups you made earlier. You can then restore and recover the database itself.
If you have failed to make backups of your recovery catalog, or if you have made the backups but are unable to use them (perhaps because you have lost parts of them), you must re-create the recovery catalog. You can re-create the recovery catalog in one of the following ways:
-
Execute the RESYNC CATALOG command to update the recovery catalog with the repository information from the control file of the target database. Of course, any aged out metadata will be lost for good.
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Execute the CATALOG START WITH . . . command to recatalog any available backups.
Cataloging Backups
You can issue the CATALOG command to catalog older backups in the recovery catalog. By issuing the CATALOG command, you can catalog older backups that have aged out of the control file, thus enabling RMAN to use those backups during a file restore operation. Here's an example that shows how to use the CATALOG command:
RMAN> CATALOG DATAFILECOPY '/u01/old_backups/users01.dbf';
You can execute the CATALOG START WITH command to catalog multiple files in a directory, as shown here:
RMAN> CATALOG START WITH '/u01/old_backups/';
RMAN waits for your confirmation after listing each file, before adding the file to the recovery catalog.
Upgrading the Recovery Catalog
If your RMAN client is from the Oracle 11.1 release, but the recovery catalog schema is from an older version, you must upgrade the recovery catalog. You can determine the schema version of the recovery catalog by executing the following query:
SQL> SELECT * FROM rcver; VERSION --------- 10.02.00
If the output of this query shows multiple rows, the highest version number is the catalog schema version. In our example, there's only one version number, 10.2.0, meaning that the catalog version is 10.2.0.
In order to upgrade the recovery catalog, follow these steps:
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If the recovery catalog owner that you created is from a release before 10.1, execute the following GRANT command (assuming that rman is the catalog owner):
SQL> GRANT CREATE TYPE TO rman;
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Start RMAN and connect to the recovery catalog database.
RMAN> connect catalog rman/rman;
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Execute the UPGRADE CATALOG command.
RMAN> UPGRADE CATALOG;
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Confirm the command by rerunning it.
RMAN> UPGRADE CATALOG;
You can now use the recovery catalog with the RMAN client from the Oracle Database 11g release.
Importing Recovery Catalogs
You may have multiple recovery catalogs, each taking care of databases from different versions of the Oracle database. You can consolidate those recovery catalogs into one catalog, by using the IMPORT CATALOG command. By default, the command imports metadata for all databases registered in the source recovery catalog to the destination recovery catalog. You can, however, specify the databases you want to import into the destination catalog. Also by default, RMAN unregisters an imported database from the source recovery catalog, but you can retain the imported databases in the source catalog by adding the NO UNREGISTER clause to the IMPORT CATALOG command.
Your target databases, recovery catalog databases, and the recovery catalog schema can be from different database versions. However, Oracle recommends that you consolidate all your recovery catalogs into a single catalog at the most recent version of the recovery catalog schema. The IMPORT CATALOG command helps you do this.
In the following example, I use the IMPORT CATALOG command to merge two recovery catalogs, one from the 10.2 release and the other from 11g, into a single 11g release catalog schema. Here are the steps:
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Connect to the destination recovery catalog.
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Issue the IMPORT CATALOG command along with the connection information for the source recovery catalog (rman10) in step 1.
RMAN> import catalog rman1/rman1@rman10; Starting import catalog at 30-MAR-08 connected to source recovery catalog database import validation complete database unregistered from the source recovery catalog Finished import catalog at 30-MAR-08 RMAN>
By default, the IMPORT CATALOG command imports all the registered databases from the source catalog into the destination catalog, but you can specify a particular database or databases, as shown here:
RMAN> import catalog rman10/rman10@tenner
dbid = 123456, 1234557;
RMAN> import catalog rman10/rman10@tenner
db_name = testdb, mydb;
The first example shows how you can specify one or more database identifiers (DBIDs), whereas the second example shows how you can give the names of databases to import. In either case, you are able to limit the import to a specific database or databases.
Moving the Recovery Catalog
You can move the recovery catalog to a different database by using the IMPORT CATALOG command. First, create an empty recovery catalog into the destination database and then issue the IMPORT CATALOG command, as shown in the following example:
$ rman RMAN> connect catalog rman/rman@target_db RMAN> import catalog rman10/rman10@source_db;
The IMPORT CATALOG command moves the recovery catalog contents to the destination database.
The IMPORT CATALOG command imports the source_db recovery catalog contents to a catalog in the target_db database.
Dropping a Recovery Catalog
Execute the DROP CATALOG command to remove a recovery catalog, as shown here:
RMAN> DROP CATALOG;
When you drop the recovery catalog, the actual backups made by RMAN will be untouched. The control files of the target database will contain records of the most recent backups made by RMAN. You can re-create the recovery catalog and register the target database to make the existing backups usable by RMAN again.