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Configuring an Oracle RAC Restore Operation to Use All Requested Streams

You can customize an RMAN restore script to force it to use the requested number of streams for a restore operation.

Oracle has an undocumented setting, SET PARALLELMEDIARESTORE OFF, which was added after Oracle 10g. This setting prevents an RMAN restore operation from checking the barcode label from the backup. In a tape-based library configuration, the barcode checking prevents RMAN from concurrently requesting backup pieces from the same media during a restore operation, which could cause reservation conflicts. If a backup used two streams, and a restore operation using more than two streams is initiated without the SET PARALLELMEDIARESTORE OFF option, RMAN uses only two streams to avoid contention.

This checking is useful for tape-based backup configurations. However, on newer systems that use disk-based libraries, there are no problems with media contention. Consequently, using the SET PARALLELMEDIARESTORE OFF option allows RMAN to use more streams for the restore operation than were used for the backup, if the backup was made using a disk-based library.

Procedure

  • In the script, add the SET PARALLELMEDIARESTORE OFF command before the run command, as shown in the following script fragment:

    SET PARALLELMEDIARESTORE OFF;
    run {
    ... Restore database commands ...
    }

Related Topics

For information about customizing the restore RMAN script, see Customizing Oracle Restore RMAN Scripts.

Last modified: 2/10/2020 6:52:48 PM