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I run this robocopy command to copy all data from the existing volume to my new volume which will replace the old one in the near future:

robocopy I:\ E:\ /E /COPYALL /PURGE /MIR /B /R:1 /W:1 /XD "Recycler" "Recycled" "$Recycle.bin" "System Volume Information" /XF "pagefile.sys" "swapfile.sys" "hiberfil.sys" /LOG:C:\Temp\copylog\logfile.log /NFL /NDL /NP

I have Dedup active on Windows 2012 Server, MS says:

Optimally, Data Deduplication should have 1 GB of memory for every 1 TB of logical data. For instance, if you are optimizing a 10 TB volume, you would optimally need 10 GB of memory allocated for Data Deduplication (1 GB * 10). This ratio will ensure the maximum performance for Data Deduplication jobs.

I have:

Old Value which needs an ckdsk and will be replaced:

Capacity 14.1 TB, Deduplication Savings 8.2 TB (34%)

I might think that the chkdsk is needed because of chunkstore problems, which would explain why it saves me 34%, even if MS says it should not save that much space.

New Volume:

Capacity 16.7 TB, Deduplication Savings 0.8 TB (4%)

And there is still missing 3 TB data which I could not copy because of missing disk space.

I read that there is no possibility to increase the deduplication rate.

How can I save some disk space on my new volume? What is safe and what not? The volume is later a part of a HA-Filecluster of MS 2012 (no R2).

donduc_jr
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  • Dedup is per volume, when you copy all the data is copied, the dedup index is not used. You should maybe do storage space replica ? which is a sector by sector replica – yagmoth555 Oct 19 '18 at 14:17
  • Have you used `Get-DedupVolume` to make sure that the dedup settings are the same on both volumes? – longneck Oct 19 '18 at 14:30
  • Maybe you have to start a dedup run (`Start-DedupJob -Volume "" -Type Optimization`) https://docs.microsoft.com/en-us/powershell/module/deduplication/start-dedupjob?view=win10-ps – Christopher Perrin Oct 19 '18 at 14:39
  • I already had run multiple dedup-job, they finished correctly: `Start-DedupJob -Type Optimization -Volume E: -Memory 90 -Cores 90 -Priority High` `Start-DedupJob -Type GarbageCollection -Volume E: -Memory 90 -Cores 90 -Priority High` Get-DedupVolume shows me nothings else what I can see in the Server Manager FS Overview – donduc_jr Oct 19 '18 at 14:54
  • Yes, but have you compared the output of `Get-DedupVolume` between the two volumes? And did you check the modify dates of the files like I suggested in your other question? – longneck Oct 19 '18 at 15:43
  • Modified Date is correct. – donduc_jr Oct 22 '18 at 08:51

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