Tuesday, October 2, 2012

ReFS and (no) Data Deduplication

Well, this post about ReFS and Data Deduplication won't be long, and for a good reason: Data Deduplication does NOT apply to partitions formatted with ReFS. Full stop. FAT32 volumes are not good either (ok, I expected this).

The only supported volume type is NTFS and the size of the partition to deduplicate must be greater than 2GB.

So, when I launched into activating Data Deduplication on my new Windows Server 2012, with the Powershell commands described here:
Import-Module ServerManager
Add-WindowsFeature -name FS-Data-Deduplication
Import-Module Deduplication
and then tried to activate it on a ReFS partition with:
Enable-DedupVolume F:
...I got this error:
Enable-DedupVolume : MSFT_DedupVolume.Volume='F:' - HRESULT 0x8056530b, The specified volume type is not supported.
Deduplication is supported on fixed, write-enabled NTFS data volumes.
At line:1 char:1
+ Enable-DedupVolume F:
+ ~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (MSFT_DedupVolume:ROOT/Microsoft/...SFT_DedupVolume) [Enable-DedupVolume],
    + FullyQualifiedErrorId : HRESULT 0x8056530b,Enable-DedupVolume
If you concentrate very hard, you should be able to see the deception on my face! After all the hype around ReFS, you are saying to me that it doesn't offer Data Deduplication?...

On the contrary, when run against a NTFS drives, the result is much more... convincing:
Enable-DedupVolume G:

Enabled SavedSpace SavingsRate Volume
------- ---------- ----------- ------
True    0 B        0 %         G:
In the end, I found out (reading here) that:

"ReFS does not itself offer deduplication. One side effect of its familiar, pluggable, file system architecture is that other deduplication products will be able to plug into ReFS the same way they do with NTFS."

I don't understand the technical choice behind this... after all, who does? I am pretty much disappointed now. I'll keep testing Data Deduplication on the other NTFS partition, but I don't see the point of introducing a brand new technology and excluding such good features!


  1. I just encountered the same problem. What sort of half-baked product is ReFS turning out to be?

    I'd been hoping that so long as MS was going to try to catch up to ZFS with file integrity (which also appears to be a half baked implementation that requires mirrored data instead of parity) that they'd include dedupe.

    Is this seriously a filesystem that's supposed to last for the next decade, as MS claims?

  2. NFS shares don't work on ReFS either...

  3. And no DFS-R Support on ReFS,


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