Win2012R2 - Dedup and space reclaim

Hawen · **Posted:** Tue Mar 24, 2015 2:52 am

Hi

I have an open supportcase with HP but I would like to know everyones experience on this.

Does Windows 2012 R2 Dedup trigger unmap and reclaim space on the 3PAR volume?

My customer has a StoreEasy NAS volume of 6TB. He filled it up with about 5,5TB data and then turned on Windows Dedup. The data was deduped down to about 4TB from the OS perspective but no space was reclaimed on the 3PAR volume.

Regards Hans

JohnMH · **Joined:** Wed Nov 19, 2014 5:14 am **Posts:** 505

Yes dedupe or more specifically the deletes caused by dedupe should trigger a reclaim, but the space will be reclaimed to the underlying volume initially. So you need to be looking at "Used User Size" not "Reserved User Size". Do a search for either of the above and you'll find lots of threads describing the differences.

Page 65 of the Windows Implementation Guide
http://h20628.www2.hp.com/km-ext/kmcsdi ... 8812-5.pdf

Hawen · **Posted:** Tue Mar 24, 2015 5:32 am

Thanks, but I am looking at "User Used Size".

Virtual Size: 6144 GiB
Used User Size: 5576 GiB
Reserved User Size: 5870 GiB
OS Reported Size after WIN dedup: ~4000GB

Tried copying 100GB to the volume and deleted it. About 10Gb was reclaimed pretty quickly.

The volume is exported to a StoreEasy NAS-cluster. I don´t know if the clustering part has anything to do with this behaviour.

My expectation was that most of the Used User Space would be reclaimed by "deletes caused by dedupe" and that the reserved user size would shrink when running compactcpg to end up with something like this. Of course with some overhead.

Virtual Size: 6144 GiB
Used User Size: ~4000 GiB
Reserved User Size: ~4100 GiB
OS Reported Size after WIN dedup: ~4000GB

Hawen · **Posted:** Tue Mar 24, 2015 6:00 am

Hmm. We are using snapshots on this volume and the change rate has pretty large the last few days as we have robocopied a bunch of files in there. About 645GB worth of snapshots. Could it be the snapshots that are locking the 3par blocks from deletion?

JohnMH · **Joined:** Wed Nov 19, 2014 5:14 am **Posts:** 505

Yes potentially, it will depend on the timing, any snaps present will keep the blocks deleted by dedupe.

If you're running StoreEasy then you might want to take a look at the BP doc and consider the SMI-S integration if it's not already in place.

http://h20195.www2.hp.com/v2/getpdf.asp ... df?ver=1.0

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Win2012R2 - Dedup and space reclaim

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