[gpfsug-discuss] How to shrink GPFS on DSSG's?

Alec anacreo at gmail.com
Mon Jun 20 21:10:04 BST 2022

In production we've come up on an FS with missing disks and GPFS just
carries on giving io errors on unusable files.. you could simply stop the
disk and bring up the FS and see what it looks like, maybe do a full backup
to null devices to make sure all the data is truely readable..  then decide
if you want to just delete the disk and add in another disk and let GPFS
recover the situation.


On Mon, Jun 20, 2022, 1:07 PM Alec <anacreo at gmail.com> wrote:

> Okay if you have double parity why not just resize the disk.  And let gpfs
> recover using the parity.  And by the way there is a qos setting for
> maintenance operations and you can give that higher priority to make the
> recovery/deleting/adding operations quicker.  Also I don't know if this
> matters in gpfs but you may want to change the affinity for disk
> (distribute the primary/first node for each disk/Christmas tree it) to a
> different servers to spread the load. I don't know if gpfs will actually
> use that to distribute load, but worth checking.
> Alec
> On Mon, Jun 20, 2022, 12:20 PM Jonathan Buzzard <
> jonathan.buzzard at strath.ac.uk> wrote:
>> On 20/06/2022 20:12, Jaime Pinto wrote:
>> >
>> > Thanks JAB and Luis
>> >
>> > I know, there are mmdelnsd, mmdeldisk, mmrestripefs and a few other
>> > correlated mm* commands. They are very high-level in work in bulk
>> > discreet fashion (I mean, considering the number of NSDs we have, each
>> > deletion will shave 4% of the storage at once, that is too much).
>> >
>> Then you are goosed. An NSD cannot be changed in size once created and
>> can only ever be in a file system or out a file system. The only way to
>> change the size of a GPFS file system is by adding or removing NSD's.
>> I am not a fan of how the DSS-G creates small numbers of huge NSD's. In
>> fact the script sucks a *lot* from a systems admin perspective. Then
>> again someone at IBM thought redeploying your entire OS every time you
>> want to make a point release upgrade was a good idea.
>> JAB.
>> --
>> Jonathan A. Buzzard                         Tel: +44141-5483420
>> HPC System Administrator, ARCHIE-WeSt.
>> University of Strathclyde, John Anderson Building, Glasgow. G4 0NG
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