Hi Eric,

On Mon, Nov 27, 2023 at 8:00 PM Eric Tittley <eric.titt...@ed.ac.uk> wrote:
>
> Hi all,
>
> For about a week our CephFS has experienced issues with its MDS.
>
> Currently the MDS is stuck in "up:rejoin"
>
> Issues become apparent when simple commands like "mv foo bar/" hung.

I assume the MDS was active at this point in time where the command
hung. Would that be correct?

>
> I unmounted CephFS offline on the clients, evicted those remaining, and then 
> issued
>
> ceph config set mds.0 mds_wipe_sessions true
> ceph config set mds.1 mds_wipe_sessions true
>
> which allowed me to delete the hung requests.

Most likely, the above steps weren't really required. The hung command
is possibly a deadlock in the MDS (during rename).

>
> I've lost the exact commands I used, but something like
> rados -p cephfs_metadata ls | grep mds
> rados rm -p cephfs_metadata mds0_openfiles.0
>
> etc
>
> This allowed the MDS to get to "up:rejoin" where it has been stuck ever since 
> which is getting on five days.
>
> # ceph mds stat
> cephfs:1/1 {0=cephfs.ceph00.uvlkrw=up:rejoin} 2 up:standby
>
>
>
> root@ceph00:/var/log/ceph/a614303a-5eb5-11ed-b492-011f01e12c9a# ceph -s
>   cluster:
>     id:     a614303a-5eb5-11ed-b492-011f01e12c9a
>     health: HEALTH_WARN
>             1 filesystem is degraded
>             1 pgs not deep-scrubbed in time
>             2 pool(s) do not have an application enabled
>             1 daemons have recently crashed
>
>   services:
>     mon: 3 daemons, quorum ceph00,ceph01,ceph02 (age 57m)
>     mgr: ceph01.lvdgyr(active, since 2h), standbys: ceph00.gpwpgs
>     mds: 1/1 daemons up, 2 standby
>     osd: 91 osds: 90 up (since 78m), 90 in (since 112m)
>
>   data:
>     volumes: 0/1 healthy, 1 recovering
>     pools:   5 pools, 1539 pgs
>     objects: 138.83M objects, 485 TiB
>     usage:   971 TiB used, 348 TiB / 1.3 PiB avail
>     pgs:     1527 active+clean
>              12   active+clean+scrubbing+deep
>
>   io:
>     client:   3.1 MiB/s rd, 3.16k op/s rd, 0 op/s wr
>
>
> # ceph --version
> ceph version 17.2.6 (d7ff0d10654d2280e08f1ab989c7cdf3064446a5) quincy (stable)
>
>
> I've tried failing the MDS so it switches.  Rebooted a couple of times.
> I've added more OSDs to the metadata pool and took one out as I thought it 
> might be a bad metadata OSD (The "recently crashed" daemon).

This isn't really going to do any good btw.

The recently crashed daemon is likely the MDS which you mentioned in
your subsequent email.

>
> The error logs are full of
> (prefix to all are:
> Nov 27 14:02:44 ceph00 bash[2145]: debug 2023-11-27T14:02:44.619+0000 
> 7f74e845e700  1 -- 
> [v2:192.168.1.128:6800/2157301677,v1:192.168.1.128:6801/2157301677] --> 
> [v2:192.168.1.133:6896/4289132926,v1:192.168.1.133:6897/4289132926]
> )
>
> crc :-1 s=READY pgs=12 cs=0 l=1 rev1=1 crypto rx=0 tx=0 comp rx=0 
> tx=0).send_message enqueueing message m=0x559be00adc00 type=42 
> osd_op(mds.0.36244:8142873 3.ff 3:ff5b34d6:::1.00000000:head [getxattr parent 
> in=6b] snapc 0=[] 
> ondisk+read+known_if_redirected+full_force+supports_pool_eio e32465) v8
> crc :-1 s=READY pgs=12 cs=0 l=1 rev1=1 crypto rx=0 tx=0 comp rx=0 
> tx=0).write_message sending message m=0x559be00adc00 seq=8142643 
> osd_op(mds.0.36244:8142873 3.ff 3:ff5b34d6:::1.00000000:head [getxattr parent 
> in=6b] snapc 0=[] 
> ondisk+read+known_if_redirected+full_force+supports_pool_eio e32465) v8
> crc :-1 s=THROTTLE_DONE pgs=12 cs=0 l=1 rev1=1 crypto rx=0 tx=0 comp rx=0 
> tx=0).handle_message got 154 + 0 + 30 byte message. envelope type=43 src 
> osd.89 off 0
> crc :-1 s=READ_MESSAGE_COMPLETE pgs=12 cs=0 l=1 rev1=1 crypto rx=0 tx=0 comp 
> rx=0 tx=0).handle_message received message m=0x559be01f4480 seq=8142643 
> from=osd.89 type=43 osd_op_reply(8142873 1.00000000 [getxattr (30) out=30b] 
> v0'0 uv560123 ondisk = 0) v8
> osd_op_reply(8142873 1.00000000 [getxattr (30) out=30b] v0'0 uv560123 ondisk 
> = 0) v8 ==== 154+0+30 (crc 0 0 0) 0x559be01f4480 con 0x559be00ad800
> osd_op(unknown.0.36244:8142874 3.ff 3:ff5b34d6:::1.00000000:head [getxattr 
> parent in=6b] snapc 0=[] 
> ondisk+read+known_if_redirected+full_force+supports_pool_eio e32465) v8 -- 
> 0x559be2caec00 con 0x559be00ad800
>
>
>
>
> Repeating multiple times a second (and filling /var)
> Prior to taking one of the cephfs_metadata OSDs offline, these came from 
> communications from ceph00 to the node hosting the suspected bad OSD.
> Now they are between ceph00 and the host of the replacement metadata OSD.
>
> Does anyone have any suggestion on how to get the MDS to switch from 
> "up:rejoin" to "up:active"?
>
> Is there any way to debug this, to determine what issue really is? I'm unable 
> to interpret the debug log.
>
> Cheers,
> Eric
>
> ________________________________________________________
> Dr Eric Tittley
> Research Computing Officer www.roe.ac.uk/~ert<http://www.roe.ac.uk/~ert>
> Institute for Astronomy Royal Observatory, Edinburgh
>
>
>
>
> The University of Edinburgh is a charitable body, registered in Scotland, 
> with registration number SC005336. Is e buidheann carthannais a th’ ann an 
> Oilthigh Dhùn Èideann, clàraichte an Alba, àireamh clàraidh SC005336.
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-- 
Cheers,
Venky
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