HPE Storage Users Group
https://3parug.com/

Reclaim free space inside VVs
https://3parug.com/viewtopic.php?f=18&t=2569		 Page 1 of 1
Author:  tntteam [ Mon Jun 26, 2017 1:36 am ]
Post subject:  Reclaim free space inside VVs
Hi there,

We have some weird problem ...

We have 2 * 7200 (FC+SSD+NL but no replicated prod data on NL so let's just say FC+SSD), the array 1 contains prod data replicated synchroneously on array 2.

We have slightly less SSD space on array 2 than 1.
I have noticed less FC space on array 2, at first I thought it was the SSD capacity difference, but no, the difference is bigger.

I have about 3.5TB (yes, TB!) more allocated data on array 2.

The FC CPG show no "free" space to compact. BUT. VVs shows free space ! How to reclaim that part ?

Some captures to illustrate :

VV on source/prod array:
Attachment:
File comment: VV on source/prod array
1.png
1.png [ 38.77 KiB | Viewed 17788 times ]


same VV on replica/backup array:
Attachment:
File comment: same VV on replica/backup array
3.png
3.png [ 39.34 KiB | Viewed 17788 times ]


CPG capacity on replica/backup array show no free space (same for ssd cpg):
Attachment:
File comment: CPG capacity on replica/backup array show no free space
5.png
5.png [ 36.57 KiB | Viewed 17788 times ]




Thanks for any idea.
Author:  tntteam [ Wed Jul 05, 2017 4:58 am ]
Post subject:  Re: Reclaim free space inside VVs
Hi there,

Is my problem crystal clear and noone has an idea about it ? Or maybe my question is not well explained ?

Thanks for any idea
Author:  MammaGutt [ Wed Jul 05, 2017 6:48 am ]
Post subject:  Re: Reclaim free space inside VVs
Can you show the output of showvv -s for the volumes?

Just a comment on the 7200... The 7200 (non-c) is the system with the lowest hardware spec of the smallest 3PAR system of the previous generation. The reclaim process is using CPU and will naturally be slower on the 7200. I've seen two replicated systems (7200 <-> 7400-2n) where the reclaim process on the 7200 was veeeeeery slow, while the 7400-2n was keeping up with day to day unmap and didn't have any problems reclaiming space from Vmware unmaps in a timely fashion.

As for SSD usage not being equal on the arrays that is very normal. AO is based on how active each 128MB regions are. One region on one array doesn't need to contain the same data as the same region on the other array. Furthermore the active array is serving both read and write for replicated volumes while the passive array is only getting the writes. So the workload will be different and AO will work different.
Author:  tntteam [ Fri Jul 07, 2017 8:13 am ]
Post subject:  Re: Reclaim free space inside VVs
showvv -s for the volume in the screenshot on the replica array :

Attachment:
Sans titre.png
Sans titre.png [ 5.26 KiB | Viewed 17652 times ]


We are not using any unmap automatic features, but I did use unmap manually on the vmware datastores level, a few times, then used compact cpg on source array and reclaimed a lot of space.
But looks like this reclaim didnt happen on replica.

So it may be slow, but atm it does nothing, the space is not reclaimed at all, even after weeks. And I can't "compact " CPG as no free space is shown.

Thanks for help
Author:  MammaGutt [ Fri Jul 07, 2017 8:57 am ]
Post subject:  Re: Reclaim free space inside VVs
Yeah.

Usr Used = 925877

Usr Rsvc = 1260928.

If 1260928 doesn't decrease anything I try this command:
showeventlog -debug -oneline -msg reclaim -min 300

This will show all reclaims for the last 5 hours (300 minutes). If this doesn't contain any information I would check the config file stored on the SP which contains the config file for the last 14 days or so (SP -> File -> serial number of the 3PAR -> timestamped config file -> View) and see if 1260928 was the number for that volume 14 days ago.

If it is the same I would log a support case to have them verify that the reclaim process is running.
Author:  tntteam [ Wed Jul 12, 2017 3:01 am ]
Post subject:  Re: Reclaim free space inside VVs
Hi,

Thanks for the debugging infos. I checked all you said, and no size is not moving, 14 days ago showvv -s show 1260928

I'll log a support request.
Author:  tntteam [ Wed Aug 30, 2017 5:02 am ]
Post subject:  Re: Reclaim free space inside VVs
Hi there,

The support show no effort to resolve this problem, after numerous mail to make them understand the problem, they finally ended telling me to convert all volumes to fully provisionned then convert back to thin.

That is not acceptable for 2 reasons : it's a lot of time and disk i/o resources, and if I'm trying to recover free space it's because I need space, I can't go thin->full, not egnouth space !

Any of you would have any idea about what to do, or what to tell to the support to make them move ?
If anyone have internal access to "CFI", one support person told me :
Quote:
There is also CFI describing slow reclamation occurring on Secondary volume when a volume is part of Remote Copy configuration – CFI 16977.

If customer wants to reclaim this space faster, they need to use workaround mentioned in CFI 16977 but the issue might occur again.

But I don't have that "CFI"... that may be a procedure or something similar...

Thanks for any help
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/