Re: [gpfsug-discuss] Data replication and fileset quotas

Wed, 04 May 2016 04:36:49 -0700

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
/spectrum_storage-banne

 
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Dr Daniel Kidger
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----- Original message -----
From: "Oesterlin, Robert" <[email protected]>
Sent by: [email protected]
To: gpfsug main discussion list <[email protected]>
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: <[email protected]> on behalf of "Simon Thompson (Research Computing - IT Services)" <[email protected]>
Reply-To: gpfsug main discussion list <[email protected]>
Date: Wednesday, May 4, 2016 at 2:11 AM
To: 'gpfsug main discussion list' <[email protected]>
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

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Simon Thompson

Research Computing Team, IT Services

+44 121 415 8675

-----Original Message-----
From: Bryan Banister [[email protected]]
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:[email protected] [mailto:[email protected]] On Behalf Of Buterbaugh, Kevin L
Sent: Tuesday, May 03, 2016 3:27 PM
To: gpfsug main discussion list <[email protected]>
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

[email protected] - (615)875-9633

 

 

 


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