[lustre-discuss] Disabling max creates and migrating data doesn't seem to be reducing the usage on an OST

Nathan Dauchy - NOAA Affiliate nathan.dauchy at noaa.gov
Wed Feb 17 13:36:12 PST 2021

On Tue, Feb 16, 2021 at 9:46 AM Kurt Strosahl <strosahl at jlab.org> wrote:

> During a maintenance window today I revooted the OSS that OST had been
> mounted on, after it came up the usage dropped significantly


That behavior you describe sounds a bit like issues reported on this list a
while back:

Data migration from one OST to anther

Migrating files doesn't free space on the OST

I thought that those problems were addressed in more recent versions of
Lustre though.  Perhaps someone else can verify that.  You aren't running a
very old version, are you?

Hope this helps,

> ------------------------------
> *From:* Iannetti, Gabriele <G.Iannetti at gsi.de>
> *Sent:* Tuesday, February 16, 2021 10:02 AM
> *To:* Kurt Strosahl <strosahl at jlab.org>; lustre-discuss at lists.lustre.org <
> lustre-discuss at lists.lustre.org>
> *Subject:* [EXTERNAL] Re: Disabling max creates and migrating data
> doesn't seem to be reducing the usage on an OST
> Hi Kurt,
> one more thing...
> The I-Node count should not increase, since new files should not be
> created on that OST.
> You can check the I-Node count with `lfs df -i | grep "\[OST:15\]"`.
> Modifications on existing files are still possible e.g. file increases in
> it's size...
> ~Gabriele
> ________________________________________
> From: lustre-discuss <lustre-discuss-bounces at lists.lustre.org> on behalf
> of Kurt Strosahl <strosahl at jlab.org>
> Sent: Thursday, February 11, 2021 16:51
> To: lustre-discuss at lists.lustre.org
> Subject: [lustre-discuss] Disabling max creates and migrating data doesn't
> seem to be reducing the usage on an OST
> Good Morning,
> One of the OSTs in a lustre file system I manage is showing a higher
> usage.  I attempted to stop writes by setting the max_create_count to zero
> and then moving data off it but that doesn't seem to be working.
> > lfs df | grep OST:15lustre19-OST000f_UUID 71145018368 62653382656
> 8491631616  89% /lustre19[OST:15]
> MDS> lctl set_param osp.lustre19-OST000f*.max_create_count=0
> MDS> lctl get_param osp.lustre19-OST000f*.max_create_count
> losp.lustre19-OST000f-osc-MDT0000.max_create_count=0
> lfs find /lustre19/expphy/volatile --ost lustre19-OST000f -size +50M |
> lfs_migrate -y
> I've been watching it, and the ost in question isn't shrinking.  I can see
> its size usage go down a bit... and then tick up a bit
> w/r,
> Kurt J. Strosahl
> System Administrator: Lustre, HPC
> Scientific Computing Group, Thomas Jefferson National Accelerator Facility
> _______________________________________________
> lustre-discuss mailing list
> lustre-discuss at lists.lustre.org
> http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
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