[gpfsug-discuss] Data replication and fileset quotas

Wed May 4 13:38:23 BST 2016

Hi Daniel,

It’s funny you mention compression & quotas – it’s something I’ve hit on a.n.other system. The supplier ended up providing different ways of presenting quotas as a mount option. Options are:

-          Quotas are tracked using the post compression/dedupe actually used space. (i.e. users see the benefit/drawback of compression)

-          Quotas are tracked using the pre compression/dedupe filesize. (i.e. the sysadmin sees the benefit; users are unaware what’s happening underneath).

Would something similar be possible in GPFS land?

David

From: gpfsug-discuss-bounces at spectrumscale.org [mailto:gpfsug-discuss-bounces at spectrumscale.org] On Behalf Of Daniel Kidger
Sent: 04 May 2016 12:36
To: gpfsug-discuss at spectrumscale.org
Cc: gpfsug-discuss at spectrumscale.org
Subject: Re: [gpfsug-discuss] Data replication and fileset quotas

As Simon says, Quota measures used blocks in the filesystem.
Hence users can and should have behaviour that keeps within these limits.

GPFS Replication though is a system-administrator level concept - to protect data access in the case of power outages or though gross hardware failures. So as such should be transparent to the end users.

Unless users are enabled to choose 1 or 2 (or 3) way replication of their own files dependent on their importance (eg 1 copy for scratch files) then imho replication should not be measured in quota reporting.

On a related note, compression is great new feature, but it may confuse users if they delete some older but big 100GB files then try and recreate them only to find they can't because their quota is now exceeded (as compression is not at file creation but driven later by policies.

Thoughts?
Daniel

Dr Daniel Kidger
IBM Technical Sales Specialist
Software Defined Solution Sales

+44-07818 522 266
daniel.kidger at uk.ibm.com<mailto:daniel.kidger at uk.ibm.com>

----- Original message -----
From: "Oesterlin, Robert" <Robert.Oesterlin at nuance.com<mailto:Robert.Oesterlin at nuance.com>>
Sent by: gpfsug-discuss-bounces at spectrumscale.org<mailto:gpfsug-discuss-bounces at spectrumscale.org>
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Cc:
Subject: Re: [gpfsug-discuss] Data replication and fileset quotas
Date: Wed, May 4, 2016 12:19 PM

From the documentation:

"When setting quota limits for a file system, replication within the file system should be considered. GPFS quota management takes replication into account when reporting on and determining if quota limits have been exceeded for both block and file usage. In a file system that has either type of replication set to a value of two, the values reported on by both the mmlsquota command and the mmrepquota command are double the value reported by the ls command."

Bob Oesterlin
Sr Storage Engineer, Nuance HPC Grid
507-269-0413

From: <gpfsug-discuss-bounces at spectrumscale.org<mailto:gpfsug-discuss-bounces at spectrumscale.org>> on behalf of "Simon Thompson (Research Computing - IT Services)" <S.J.Thompson at bham.ac.uk<mailto:S.J.Thompson at bham.ac.uk>>
Reply-To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org<mailto:gpfsug-discuss at spectrumscale.org>>
Date: Wednesday, May 4, 2016 at 2:11 AM
To: 'gpfsug main discussion list' <gpfsug-discuss at spectrumscale.org<mailto:gpfsug-discuss at spectrumscale.org>>
Subject: [EXTERNAL] Re: [gpfsug-discuss] Data replication and fileset quotas

Yes, this correct (I think there was some discussion on the mailing list a little while back).

The quota is the space used on disk, so if you run compression its the compressed size, tape hsm don't count until you recall them.

I assume mcstore is the same, I.e. Only counts on recall, but I haven't tested this.

Simon

--

Simon Thompson

Research Computing Team, IT Services

+44 121 415 8675

-----Original Message-----
From: Bryan Banister [bbanister at jumptrading.com<mailto:bbanister at jumptrading.com>]
Sent: Tuesday, May 03, 2016 09:33 PM GMT Standard Time
To: gpfsug main discussion list
Subject: Re: [gpfsug-discuss] Data replication and fileset quotas

Yes, I believe that is the case due to the fact that every file is replicated therefore taking twice as much space within the file system.

-Bryan

From:gpfsug-discuss-bounces at spectrumscale.org<mailto:gpfsug-discuss-bounces at spectrumscale.org> [mailto:gpfsug-discuss-bounces at spectrumscale.org] On Behalf Of Buterbaugh, Kevin L
Sent: Tuesday, May 03, 2016 3:27 PM
To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org<mailto:gpfsug-discuss at spectrumscale.org>>
Subject: [gpfsug-discuss] Data replication and fileset quotas

Hi again all,

I have another question on a completely different topic and therefore I decided it was better to send two separate e-mails.

For a number of years now we have had a GPFS filesystem where we use filesets and set fileset quotas.  Data replication is set to one.  I understand how that all works.

We are creating another GPFS filesystem where we intend to also use filesets and fileset quotas, but set data replication to two.  Based on my experience with data replication on a filesystem that doesn’t use filesets, I am expecting that setting data replication to two means that I will need to double the quota for each fileset (i.e. if a group has bought 5 TB of space I’ll need to set their fileset quota to 10 TB) but haven’t found where that is explicitly documented.  Is that correct?

Thanks again, all…

Kevin

—

Kevin Buterbaugh - Senior System Administrator

Vanderbilt University - Advanced Computing Center for Research and Education

Kevin.Buterbaugh at vanderbilt.edu<mailto:Kevin.Buterbaugh at vanderbilt.edu> - (615)875-9633

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