Manual space reclamation for Deduplication Storage Folder in Backup Exec

Article:TECH192557  |  Created: 2012-07-08  |  Updated: 2014-11-27  |  Article URL http://www.symantec.com/docs/TECH192557
Article Type
Technical Solution

Product(s)

Issue



Disk space is not being reclaimed fast enough and a manual space reclamation for a Deduplication Storage Folder is necessary to quickly make space available on the volume.


Solution



Backup Exec automatically deletes expired media and makes the space available to the Deduplication Folder.  If it is necessary to quickly make some space available, the Backup Administrator can manually delete unnecessary backups and quickly free up that space for use in subsequent backup jobs.  However, it is likely that this situation will recur unless the Backup Administrator either reduces the amount of data saved on the deduplication folder (by reducing media retention times), or increases the amount of space available to the Deduplication Folder.

Backup Exec 2012 and newer, provides the list of Backup Sets in the Storage Tab. To reclaim space in deduplication storage folder the unwanted or less important backup sets need to be deleted manually. This Backup set selection needs to be done by the Backup Administrator. Please note that Backup Exec will only free the space within the Deduplication Folder containers and will not release space to the file system.  That is, at the end of this process, the properties of the Deduplication Folder should show that space has been made available.  However, looking at the volume from the Windows Explorer view will not show space being freed up. Follow these steps:

  • Delete the Backup Sets from Storage tab, Backup Sets, as shown in below figure.

 

  •  The Backup sets vanish and deletion from the UI will also initiate a deletion of these sets permanently from the deduplication folder. This deletion will generate a number of tlogs in the Deduplication queue folder which will have to be processed to reclaim space.  This just means that Backup Exec has informed the Deduplication engine that these sets are no longer needed.  This normally gets processed (queue processing) every 12 hours.
Note : By default queue processing runs every 12 hours. Sched_QueueProcess.log records when queue processing gets initiated by PDDE. This log is located in DeduplicationFolderPath\Log\Spad.

 

  •  To process the tlogs from the queue folder 2 rounds of processqueue needs to be run. This means that the Backup administrator will have to execute crcontrol.exe --processqueue twice from the Backup Exec Install path. On production setup when the processqueue is run twice, Busy and Pending would both show up YES.

 

  •  Queue process activity can be captured in storaged.log. This is located at DeduplicationStoragePath\Log\Spoold folder.

  •  Initiate a garbage collection after queue processing completes i.e. processqueueinfo returns Busy : No Pending : No. Garbage collection can be initiated by running crcollect -v -m +1,+2 from the Backup Exec Install path.  This will again produce tlogs in the queue folder which should be processed by executing crcontrol.exe --processqueue twice.
  • Compaction should be started when 2 rounds of queue processing are completed after garbage collection and processqueueinfo show 'Busy: No' , 'Pending: No'.

To start the compaction process execute crcontrol.exe --compactstart. Crcontrol.exe --compactstate can be run to check the status of compaction

C:\Program Files\Symantec\Backup Exec>crcontrol.exe --compactstate
Data store compaction: ON, DeleteSpaceThreshold: 1%, CompactLBound: 1MB
Compaction busy: Yes

  • After performing the above activity in order space usage can be checked by initiating crstats --convert-size.

Note: Even with all of this, one has to remember that the entire purpose of a deduplication folder is to try to keep only one copy of data in the folder no matter how many times it has been backed up. 
 
Example: If there are 5 pieces of media that have full backups of a particular system and the above procedure to delete 4 of those 5 media, very little space will be reclaimed. This is because all 5 pieces of media reference one copy of the data. A particular chunk of data can't be erased and the space freed until all references to it have been deleted first.





Article URL http://www.symantec.com/docs/TECH192557


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