[gpfsug-discuss] dependent versus independent filesets

Wahl, Edward ewahl at osc.edu
Tue Jul 7 15:44:16 BST 2020


We also went with independent filesets for both backup (and quota) reasons for several years now, and have stuck with this across to 5.x.  However we still maintain a minor number of dependent filesets for administrative use.     Being able to mmbackup on many filesets at once can increase your parallelization _quite_ nicely!  We create and delete the individual snaps before and after each backup, as you may expect.  Just be aware that if you do massive numbers of fast snapshot deletes and creates you WILL reach a point where you will run into issues due to quiescing compute clients, and that certain types of workloads have issues with snapshotting in general. 

You have to more closely watch what you pre-allocate, and what you have left in the common metadata/inode pool.  Once allocated, even if not being used, you cannot reduce the inode allocation without removing the fileset and re-creating.  (say a fileset user had 5 million inodes and now only needs 500,000)   

Growth can also be an issue if you do NOT fully pre-allocate each space.  This can be scary if you are not used to over-subscription in general.  But I imagine that most sites have some decent % of oversubscription if they use filesets and quotas. 

Ed
OSC

-----Original Message-----
From: gpfsug-discuss-bounces at spectrumscale.org <gpfsug-discuss-bounces at spectrumscale.org> On Behalf Of Skylar Thompson
Sent: Tuesday, July 7, 2020 10:00 AM
To: gpfsug-discuss at spectrumscale.org
Subject: Re: [gpfsug-discuss] dependent versus independent filesets

We wanted to be able to snapshot and backup filesets separately with mmbackup, so went with independent filesets.

On Tue, Jul 07, 2020 at 08:37:46AM -0500, Damir Krstic wrote:
> We are deploying our new ESS and are considering moving to independent 
> filesets. The snapshot per fileset feature appeals to us.
> 
> Has anyone considered independent vs. dependent filesets and what was 
> your reasoning to go with one as opposed to the other? Or perhaps you 
> opted to have both on your filesystem, and if, what was the reasoning for it?
> 
> Thank you.
> Damir

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-- Skylar Thompson (skylar2 at u.washington.edu)
-- Genome Sciences Department (UW Medicine), System Administrator
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