[gpfsug-discuss] GPFS Independent Fileset Limit

Doug Johnson djohnson at osc.edu
Fri Aug 10 16:22:23 BST 2018


Hi all,

I want to chime in because this is precisely what we have done at OSC
due to the same motivations Janell described.  Our design was based in
part on the guidelines in the "Petascale Data Protection" white paper
from IBM.  We only have ~200 filesets and 250M inodes today, but expect
to grow.

We are also very interested in details about performance issues and
independent filesets.  Can IBM elaborate?

Best,
Doug


Martin Lischewski <m.lischewski at fz-juelich.de> writes:

> Hello Olaf, hello Marc,
>
> we in Jülich are in the middle of migrating/copying all our old filesystems which were created with filesystem
> version: 13.23 (3.5.0.7) to new filesystems created with GPFS 5.0.1.
>
> We move to new filesystems mainly for two reasons: 1. We want to use the new increased number of subblocks.
> 2. We have to change our quota from normal "group-quota per filesystem" to "fileset-quota".
>
> The idea is to create a separate fileset for each group/project. For the users the quota-computation should be
> much more transparent. From now on all data which is stored inside of their directory (fileset) counts for their
> quota independent of the ownership.
>
> Right now we have round about 900 groups which means we will create round about 900 filesets per filesystem.
> In one filesystem we will have about 400million inodes (with rising tendency).
>
> This filesystem we will back up with "mmbackup" so we talked with Dominic Mueller-Wicke and he recommended
> us to use independent filesets. Because then the policy-runs can be parallelized and we can increase the backup
> performance. We belive that we require these parallelized policies run to meet our backup performance targets.
>
> But there are even more features we enable by using independet filesets. E.g. "Fileset level snapshots" and "user
> and group quotas inside of a fileset".
>
> I did not know about performance issues regarding independent filesets... Can you give us some more
> information about this?
>
> All in all we are strongly supporting the idea of increasing this limit.
>
> Do I understand correctly that by opening a PMR IBM allows to increase this limit on special sides? I would rather
> like to increase the limit and make it official public available and supported.
>
> Regards,
>
> Martin
>
> Am 10.08.2018 um 14:51 schrieb Olaf Weiser:
>
>  Hallo Stephan,
>  the limit is not a hard coded limit - technically spoken, you can raise it easily.
>  But as always, it is a question of test 'n support ..
>
>  I've seen customer cases, where the use of much smaller amount of independent filesets generates a lot
>  performance issues, hangs ... at least noise and partial trouble ..
>  it might be not the case with your specific workload, because due to the fact, that you 're running already
>  close to 1000 ...
>
>  I suspect , this number of 1000 file sets - at the time of introducing it - was as also just that one had to pick a
>  number...
>
>  ... turns out.. that a general commitment to support > 1000 ind.fileset is more or less hard.. because what
>  uses cases should we test / support
>  I think , there might be a good chance for you , that for your specific workload, one would allow and support
>  more than 1000
>
>  do you still have a PMR for your side for this ? - if not - I know .. open PMRs is an additional ...but could you
>  please ..
>  then we can decide .. if raising the limit is an option for you ..
>
>  Mit freundlichen Grüßen / Kind regards
>
>  Olaf Weiser
>
>  EMEA Storage Competence Center Mainz, German / IBM Systems, Storage Platform,
>  -------------------------------------------------------------------------------------------------------------------------------------------
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>  71139 Ehningen
>  Phone: +49-170-579-44-66
>  E-Mail: olaf.weiser at de.ibm.com
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>
>  From: "Peinkofer, Stephan" <Stephan.Peinkofer at lrz.de>
>  To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
>  Cc: Doris Franke <doris.franke at de.ibm.com>, Uwe Tron <utron at lenovo.com>, Dorian Krause
>  <d.krause at fz-juelich.de>
>  Date: 08/10/2018 01:29 PM
>  Subject: [gpfsug-discuss] GPFS Independent Fileset Limit
>  Sent by: gpfsug-discuss-bounces at spectrumscale.org
> ---------------------------------------------------------------------------------------------------
>
>  Dear IBM and GPFS List,
>
>  we at the Leibniz Supercomputing Centre and our GCS Partners from the Jülich Supercomputing Centre will
>  soon be hitting the current Independent Fileset Limit of 1000 on a number of our GPFS Filesystems.
>
>  There are also a number of RFEs from other users open, that target this limitation:
>  https://www.ibm.com/developerworks/rfe/execute?use_case=viewRfe&CR_ID=56780
>  https://www.ibm.com/developerworks/rfe/execute?use_case=viewRfe&CR_ID=120534
>  https://www.ibm.com/developerworks/rfe/execute?use_case=viewRfe&CR_ID=106530
>  https://www.ibm.com/developerworks/rfe/execute?use_case=viewRfe&CR_ID=85282
>
>  I know GPFS Development was very busy fulfilling the CORAL requirements but maybe now there is again
>  some time to improve something else.
>
>  If there are any other users on the list that are approaching the current limitation in independent filesets,
>  please take some time and vote for the RFEs above.
>
>  Many thanks in advance and have a nice weekend.
>  Best Regards,
>  Stephan Peinkofer
>
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