Configuring the Disk Ratio for Oracle RMAN

The Oracle disk ratio groups the data files into backup sets, distributes the backup load across the disks and enhances backup performance.

The restore performance is slower when a larger number of disks are grouped together, so set the disk ratio to a minimum.

By default, the RMAN disk ratio is not set.


  1. From the CommCell Browser, expand Client Computers > client > Oracle > instance.
  2. Right-click the subclient and click Backup.
  3. On the Backup Options dialog box click Advanced.

    The Advanced Backup Options dialog box appears.

  4. On the Oracle Options tab:
    1. Select the Enable Rman Disk Ratio check box.
    2. Select the number of disks for the backup, in the Rman Disk Ratio box, type the number of disks.
    3. Click OK to close the Advanced Backup Options dialog box.
  5. Click OK to close the Backup Options dialog box.


If data files are distributed across 10 disks that supply data at 10 bytes/second and a tape drive that needs 50 bytes/second to keep streaming, set the disk ratio value to 5. This value directs RMAN to include data files from 5 disks in each backup set.