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 Post subject: understanding dedup in 3.3.1
PostPosted: Wed Sep 12, 2018 1:28 am 

Joined: Fri Aug 10, 2018 3:13 pm
Posts: 6
I have just update to 3.3.1 MU2.
After that in the 3par management console version 4.7.3 under virtual volumes I have a new volume named .sysvv_0SSD_r5 that was not ther before.
If I use SSMC I do not see that volume.
Then I have the virtual volume published to xenserver hosts.
Here what I see:
Total used: 24,14 GiB
Virtual size: 7.144,00 GiB
Total reserved 24,50 GiB
Host written 1.639,11 GiB

and it says used 0%

If I make the sum of my VM I have about 2TB, considering that disk are not full I am guessing that the value in Host written is correct with the space used by VM.

So how is possible that total reserved is 24GB only?

In that hidden virtual volume ( .sysvv_0SSD_r5) I have 1.2 TB


Someone can explain to me how 3.3.1 use space? thanks


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 Post subject: Re: understanding dedup in 3.3.1
PostPosted: Wed Sep 12, 2018 8:40 am 

Joined: Wed Nov 19, 2014 5:14 am
Posts: 504
.sysvv_0SSD_r5 is the common dedupe store for the CPG, with 3.3.1 matching pages will be stored in this volume, unique pages will be stored in the regular VV you present to the host, unless there is a match in which case it will be migrated to the dedupe store. So the two combined will be the sum of the data stored on the backend.

See this whitepaper for more detail https://h20195.www2.hpe.com/v2/getdocument.aspx?docname=a00006358enw

"The dedup ratio of a CPG is the sum of all the data written (host written) to the deduplicated volumes divided by the sum of the data stored in the volumes and the data associated with the volumes in the Dedup Store."


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 Post subject: Re: understanding dedup in 3.3.1
PostPosted: Wed Sep 12, 2018 3:01 pm 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 712
Location: Europe
.sysvv is tdvv1/2. Tdvv3 should be .shared if my memory serves me right. Showcpg -d should show dds version I think.


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 Post subject: Re: understanding dedup in 3.3.1
PostPosted: Thu Sep 13, 2018 9:52 am 

Joined: Fri Aug 10, 2018 3:13 pm
Posts: 6
MammaGutt wrote:
.sysvv is tdvv1/2. Tdvv3 should be .shared if my memory serves me right. Showcpg -d should show dds version I think.


Here the output:
cli% showcpg -d
----Volumes---- -Usage- ----------(MiB)----------- --LD--- -RC_Usage- -Shared-
Id Name Warn% VVs TPVVs TDVVs Usr Snp Base Snp Free Total Usr Snp Usr Snp Version
0 FC_r1 - 0 0 0 0 0 0 0 0 0 0 0 0 0 -
1 FC_r5 - 1 0 0 1 0 6967296 0 0 6967296 13 0 0 0 -
5 FC_r6 - 0 0 0 0 0 0 0 0 0 0 0 0 0 -
2 SSD_r1 - 0 0 0 0 0 0 0 0 0 0 0 0 0 -
3 SSD_r5 - 2 0 1 2 0 1522688 0 602112 2434816 0 10 0 0 2
4 SSD_r6 - 0 0 0 0 0 0 0 0 0 0 0 0 0 -
----------------------------------------------------------------------------------------------
6 total 3 0 8489984 0 602112 9402112 13 10 0 0

what is tdvv3? I have just upgrade to 3.3.1 but the cpgs and virtual volumes where created before with 3.2.2
I have done a tune on the virtual volume. Is there anything else I have to do to use the increased depup performance of 3.3.1?


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 Post subject: Re: understanding dedup in 3.3.1
PostPosted: Thu Sep 13, 2018 3:08 pm 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 712
Location: Europe
You need to create a new CPG and tune all volumes to that CPG or convert all tdvvs to tpvv and once all are gone you convert them back.


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