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Reclaim Deduplicated Space on a Server 2012 Server

Hello.  I have a server 2012 veeam backup server that has been storing our Veeam Backups for the past 9 months.  That backup archive volume is 26TB which now only has 3 TB available.  We were able to achieve a 73% deduplication rate.  
Our weekly full backups are 4 TB so we are now out of space.  I have gone through and deleted 4 months of backups but since they are deduplicated I don't get the space savings back that I thought I was going to get.

I have stopped the current running deduplication job until I can fix this issue.  I have ran the full and basic garbage collection job but have been unable to reclaim enough space to store new backups.  It only freed up about 2 TB or so.  

Start-DedupJob -Type GarbageCollection -full -Memory 85 -Priority High -Volume A:

Does anyone know how I can reclaim space on a deduplicated volume?


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Cliff GaliherCommented:
For the built-in windows dedup, you *have* to let it finish. Because it uses dynamic chunk sizes and some back-end trickery, space cannot be released until all of the blocks have been mapped/recapped. From there, the space will be freed automatically.
PapnouAuthor Commented:
Thanks.  Do you know if Server 2012 R2 Deduplication allows for files larger than 1 TB to be deduplicated?  I heard it will allow for up to 3 TB files but the documentation states otherwise.   My issues I think are stemming from my veeam backup files being 1.5 TB each.  We group our jobs by OS type as they are deduped within the backup job as well.

Requirements for Data Deduplication
Files approaching or larger than 1 TB in size.
Cliff GaliherCommented:
No. In general, deduping 3rd-party backups are prone to issues because most backup vendors (Veeam for certain) use some driver trickery to speed up their backups. They aren't using native OS calls. You'll have many issues attempting to use dedup as you sre.l, file size being the least of the hurdles.
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