How to get Advanced Open File Option to snap one volume at a time during multi-volume backups

Problem

How to get Advanced Open File Option to snap one volume at a time during multi-volume backups

Solution

 Performing Advanced Open File Option (AOFO) backups of multiple volumes on a single server using the default settings may cause one or more of the following errors:

Final error code: a00084af HEX Final error description: Directory or File was not found, or could not be accessed.
OFO: Snapshot error (0xa000851c): VSP SnapShot CacheFileBroker was unable to allocate cache files. Check disk space.
OFO: Unable to get minimum quiet time window for physical volume.
OFO: Backup Exec failed to establish communication with the Advanced Open File Option component. A reinstallation of the Advanced Open File Option is probably necessary.

The Advanced Open File Option creates a snapshot of each volume being backed up, in order to maintain a point-in-time consistent backup. When changes are made to the volume, the pre-change version of the data is saved to the cache file and the new data is written to the volume. When it is time to back up that data, the pre-change data in the cache file is backed up. By default, when backing up multiple volumes on a server in a single job, AOFO creates a cache file for all volumes simultaneously. The benefit to this is that all volumes on that server are point-in-time consistent in the backup. There are several environmental factors that occasionally make this scenario undesirable.

In Backup Exec (tm) 9.1 a new feature that allows the user to disable the multi-volume snap was introduced. This allowed AOFO to create the snapshot and the corresponding cache file one at a time, thus limiting the environmental impact of using AOFO.

To enable Single Volume Cache, perform the following:
Note: This is a global setting that affects all jobs run from this media server.

1. Open Regedt32 from Start | Run

Warning: Incorrect use of the Windows registry editor may prevent the operating system from functioning properly. Great care should be taken when making changes to a Windows registry. Registry modifications should only be carried-out by persons experienced in the use of the registry editor application. It is recommended that a complete backup of the registry and workstation be made prior to making any registry changes.

2. Browse to

HKEY_LOCAL_MACHINE\SOFTWARE\VERITAS\Backup Exec\Engine\Backup for Backup Exec 10.x and below (Figure 1)
 

or

HKEY_LOCAL_MACHINE\SOFTWARE\veritas\Backup Exec For Windows\Backup Exec\Engine\Backup for Backup Exec 11d and above

Figure 1



3. Double-click DoSingleVolumeSnap and change the Value to 1 (Figure 2)
 

Figure 2


 

4. Close the registry editor


In Backup Exec 10.0 and above, the same can also be done on per job basis.

1. Click the Backup button to create a new job
2. In the backup job properties, under Settings, select Advanced Open File
3. Select the check box Use Advanced Open File Option
4. To enable single volume cache, select the option Process Logical Volumes for backup one at a time (Figure 3)

Figure 3