Can you tell if the number of objects increases in your cephfs between
those bursts? I noticed something similar in a 16.2.15 cluster as
well. It's not that heavily used, but it contains home directories and
development working directories etc. And when one user checked out a
git project, the mds memory usage increased a lot, getting near its
configured limit. Before there were around 3,7 Million objects in the
cephfs, that user added more than a million more files with his
checkout. It wasn't a real issue (yet) because the usage isn't very
dynamical and the total number of files is relatively stable.
This doesn't really help resolve anything, but if your total number of
files grows, I'm not surprised that the mds requires more memory.
Zitat von Alexander Patrakov <patrakov@xxxxxxxxx>:
As a workaround, to reduce the impact of the MDS slowed down by
excessive memory consumption, I would suggest installing earlyoom,
disabling swap, and configuring earlyoom as follows (usually through
/etc/sysconfig/earlyoom, but could be in a different place on your
distribution):
EARLYOOM_ARGS="-p -r 600 -m 4,4 -s 1,1"
On Sat, Aug 31, 2024 at 3:44 PM Sake Ceph <ceph@xxxxxxxxxxx> wrote:
Ow it got worse after the upgrade to Reef (was running Quincy).
With Quincy the memory usage was also a lot of times around 95% and
some swap usage, but never exceeding both to the point of crashing.
Kind regards,
Sake
> Op 31-08-2024 09:15 CEST schreef Alexander Patrakov <patrakov@xxxxxxxxx>:
>
>
> Got it.
>
> However, to narrow down the issue, I suggest that you test whether it
> still exists after the following changes:
>
> 1. Reduce max_mds to 1.
> 2. Do not reduce max_mds to 1, but migrate all clients from a direct
> CephFS mount to NFS.
>
> On Sat, Aug 31, 2024 at 2:55 PM Sake Ceph <ceph@xxxxxxxxxxx> wrote:
> >
> > I was talking about the hosts where the MDS containers are
running on. The clients are all RHEL 9.
> >
> > Kind regards,
> > Sake
> >
> > > Op 31-08-2024 08:34 CEST schreef Alexander Patrakov
<patrakov@xxxxxxxxx>:
> > >
> > >
> > > Hello Sake,
> > >
> > > The combination of two active MDSs and RHEL8 does ring a bell, and I
> > > have seen this with Quincy, too. However, what's relevant is the
> > > kernel version on the clients. If they run the default 4.18.x kernel
> > > from RHEL8, please either upgrade to the mainline kernel or decrease
> > > max_mds to 1. If they run a modern kernel, then it is something I do
> > > not know about.
> > >
> > > On Sat, Aug 31, 2024 at 1:21 PM Sake Ceph <ceph@xxxxxxxxxxx> wrote:
> > > >
> > > > @Anthony: it's a small virtualized cluster and indeed SWAP
shouldn't be used, but this doesn't change the problem.
> > > >
> > > > @Alexander: the problem is in the active nodes, the standby
replay don't have issues anymore.
> > > >
> > > > Last night's backup run increased the memory usage to 86%
when rsync was running for app2. It dropped to 77,8% when it was
done. When the rsync for app4 was running it increased to 84% and
dropping to 80%. After a few hours it's now settled on 82%.
> > > > It looks to me the MDS server is caching something forever
while it isn't being used..
> > > >
> > > > The underlying host is running on RHEL 8. Upgrade to RHEL 9
is planned, but hit some issues with automatically upgrading hosts.
> > > >
> > > > Kind regards,
> > > > Sake
> > > > _______________________________________________
> > > > ceph-users mailing list -- ceph-users@xxxxxxx
> > > > To unsubscribe send an email to ceph-users-leave@xxxxxxx
> > >
> > >
> > >
> > > --
> > > Alexander Patrakov
>
>
>
> --
> Alexander Patrakov
> _______________________________________________
> ceph-users mailing list -- ceph-users@xxxxxxx
> To unsubscribe send an email to ceph-users-leave@xxxxxxx
_______________________________________________
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx
--
Alexander Patrakov
_______________________________________________
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx
_______________________________________________
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx
