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 Post subject: Space reclaim on shared space in CPG
PostPosted: Fri Jun 28, 2019 11:29 pm 
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Joined: Wed Aug 26, 2015 5:32 am
Posts: 3
Hi folks,

we are implementing a new all-flash 3PAR 8400.

For test purposes we deleted all volumes of a CPG except one, to check if the space reclaim process of the shared space (dedup) is working.

Unfortunately the amount of data in the shared space remained exactly the same, even after a "compact cpg". The shared space of the CPG is now mutch bigger then the last volume on it. Is there a option which we miss?

If not, how do you deal with this issue? For example, after some time you have big appliactions with good dedup-results which are going to be replaced. If the shared space is never cleaned up, its only getting bigger. Do you on regular basis recreate the CPGs and do you use more than one CPG to seperate the applications?

Out first idea was to use only one CPG for the best dedup-results, it seams not a good idea if we have to recreate it.

Best regards,
fcguy


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 Post subject: Re: Space reclaim on shared space in CPG
PostPosted: Sat Jun 29, 2019 3:08 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 957
Location: Europe
What 3PAR OS?

Tdvv2 (dedupe cpg created on 3.2.2) it would take ages.
Tdvv3 (dedupe cpg created on 3.3.1) works better.

There are some recleam bugs fixed in 3.3.1 MU2 P76 and 3.2.2 MU6 P144 if I recall correctly so unless you're using latest and greatest those might be an issue for you.

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 Post subject: Re: Space reclaim on shared space in CPG
PostPosted: Sat Jun 29, 2019 3:21 am 
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Joined: Wed Aug 26, 2015 5:32 am
Posts: 3
MammaGutt wrote:
What 3PAR OS?

Tdvv2 (dedupe cpg created on 3.2.2) it would take ages.
Tdvv3 (dedupe cpg created on 3.3.1) works better.

There are some recleam bugs fixed in 3.3.1 MU2 P76 and 3.2.2 MU6 P144 if I recall correctly so unless you're using latest and greatest those might be an issue for you.


Hi MammaGutt,

thank you. We are using TDVV3 on 3.3.1 MU3 with patches P50/58/61/77/78, so I think the patches you mentioned should be included.

You are sure that there is a space reclaim process for the "shared space" area of a CPG? Can this process manualy be triggert?

Best regards,
fcguy


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 Post subject: Re: Space reclaim on shared space in CPG
PostPosted: Sat Jun 29, 2019 4:30 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 957
Location: Europe
Can't be triggered manually.

Showeventlog -oneline -debug -msg "reclaim history" -min 1440
Should show any reclaim happening on all volumes. If you doesn't see anything there you should try
Showeventlog -oneline -debug -msg "cand" -min 1440
To see if it triggers a defrag due to lack of reclaim.

If you see no reclaim or defrag I would log a case.

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