[gpfsug-discuss] gpfs snapshots

Tue Sep 13 22:21:59 BST 2016

I thought the GUI implemented some form of snapshot scheduler. Personal opinion is that is the wrong place and I agree that is should be core functionality to ensure that the scheduler is running properly.

But I would suggest that it might be more than just snapshots people might want to schedule. E.g. An ilm pool flush.

Simon
________________________________________
From: gpfsug-discuss-bounces at spectrumscale.org [gpfsug-discuss-bounces at spectrumscale.org] on behalf of Yuri L Volobuev [volobuev at us.ibm.com]
Sent: 13 September 2016 21:51
To: gpfsug main discussion list
Subject: Re: [gpfsug-discuss] gpfs snapshots

Hi Jez,

It sounds to me like the functionality that you're _really_ looking for is an ability to to do automated snapshot management, similar to what's available on other storage systems. For example, "create a new snapshot of filesets X, Y, Z every 30 min, keep the last 16 snapshots". I've seen many examples of sysadmins rolling their own snapshot management system along those lines, and an ability to add an expiration string as a snapshot "comment" appears to be merely an aid in keeping such DIY snapshot management scripts a bit simpler -- not by much though. The end user would still be on the hook for some heavy lifting, in particular figuring out a way to run an equivalent of a cluster-aware cron with acceptable fault tolerance semantics. That is, if a snapshot creation is scheduled, only one node in the cluster should attempt to create the snapshot, but if that node fails, another node needs to step in (as opposed to skipping the scheduled snapshot creation). This is doable outside of GPFS, of course, but is not trivial. Architecturally, the right place to implement a fault-tolerant cluster-aware scheduling framework is GPFS itself, as the most complex pieces are already there. We have some plans for work along those lines, but if you want to reinforce the point with an RFE, that would be fine, too.

yuri

[Inactive hide details for Jez Tucker ---09/13/2016 02:10:31 AM---Hey Yuri,    Perhaps an RFE here, but could I suggest there is]Jez Tucker ---09/13/2016 02:10:31 AM---Hey Yuri, Perhaps an RFE here, but could I suggest there is much value in

From: Jez Tucker <jtucker at pixitmedia.com>
To: gpfsug-discuss at spectrumscale.org,
Date: 09/13/2016 02:10 AM
Subject: Re: [gpfsug-discuss] gpfs snapshots
Sent by: gpfsug-discuss-bounces at spectrumscale.org

________________________________

Hey Yuri,

  Perhaps an RFE here, but could I suggest there is much value in adding a -c <comment> option to mmcrsnapshot?

Use cases:

mmcrsnapshot myfsname @GMT-2016.09.13-10.00.00 -j myfilesetname -c "Before phase 2"

and

mmcrsnapshot myfsname @GMT-2016.09.13-10.00.00 -j myfilesetname -c "expire:GMT-2017.04.21-16.00.00"

Ideally also: mmcrsnapshot fs1 fset1:snapA:expirestr,fset2:snapB:expirestr,fset3:snapC:expirestr

Then it's easy to iterate over snapshots and subsequently mmdelsnapshot snaps which are no longer required.
There are lots of methods to achieve this, but without external databases / suchlike, this is rather simple and effective for end users.

Alternatively a second comment like -expire flag as user metadata may be preferential.

Thoughts?

Jez

On 13/09/16 05:32, Valdis.Kletnieks at vt.edu<mailto:Valdis.Kletnieks at vt.edu> wrote:

On Tue, 13 Sep 2016 00:30:19 +0200, Lukas Hejtmanek said:
I guess we could reach snapid 100,000.

It probably stores the snap ID as a 32 or 64 bit int, so 100K is peanuts.

What you *do* want to do is make the snap *name* meaningful, using
a timestamp or something to keep your sanity.

mmcrsnapshot fs923 `date +%y%m%d-%H%M`   or similar.
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--
Jez Tucker
Head of Research & Product Development
Pixit Media
www.pixitmedia.com<http://www.pixitmedia.com/>

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