Manual space reclamation for Deduplication Storage Folder in Backup Exec 2012 and above.

Problem

The Deduplication Drive may fill up due to longer retention or increase in the size and kind of data being backed up over a period of time. In this scenario, the Deduplication Storage Folder Drive can be extended or some backup sets can be deleted/expired manually to make some room for newer Backup Sets.

Solution

Backup Exec automatically deletes expired media/backup sets and makes the space available to the Deduplication Folder.  If there is a need to make more room inside the Deduplication Storage containers ( i.e. the Bin and Bhd files residing in DedupeStorageLocation\Data folder), the Backup administrator can manually delete backup sets and free up some space. 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/backup set retention), 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 less important backup sets can be identified or if they are needed a duplicate to another storage can be run for them and then these sets can be deleted/expired 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 may not show space being freed up. Follow these steps:

  • Delete (BE 2012) or Expire (2014/15) the Backup Sets from Storage tab, Backup Sets, as shown in below figures.

 





 

  •  The Backup sets should vanish post deletion and expire. This 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 (PureDisk Deduplication Engine). This log is located in DeduplicationFolderPath\Log\Spad.

 

  •  To manually process the tlogs from the queue folder run the processqueue command 2 times. This means that the Backup administrator will have to execute crcontrol.exe --processqueue twice from the Backup Exec Install path. On a production setup when the processqueue is run twice and processqueueinfo command is run to check the state of processqueue, 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. Remember to run this before and after space reclamation is done. Avoid running Backups to Deduplication Storage Folder while getting the space back since the difference cannot be made if the backups are still being done and at the same time the other backup sets are being deleted. Backup Exec 2014/15 uses a newer Dedupe Engine as compared to BE 2010 R3 and BE 2012 so queue processing performance is faster than earlier.

    Note: The Deduplication Storage Folder houses unique chunks and hence most of the backup sets may be pointing to the same chunks or atleast a few. It is important to know that very less space may be released if the Deduplication Ratio is very high. The reason for this is the space only reclaims when all backup sets referenced to the unique chunk are deleted, that marks the chunk is not required and that is deleted also. This is how the space is reclaimed so it is important to note that more Backup sets may need to be deleted/expired to release a good amount of space for future backups to take place on the same Deduplication Storage Folder.

Terms of use for this information are found in Legal Notices.

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