Hello Linkriver I might have an issue close to your Can you tell us if your strays dirs are full ? What does this command output to you ? ceph tell mds.0 perf dump | grep strays Does the value change over time ? All the best Arnaud Le mer. 16 mars 2022 à 15:35, Linkriver Technology < technology@xxxxxxxxxxxxxxxxxxxxx> a écrit : > Hi, > > Has anyone figured whether those "lost" snaps are rediscoverable / > trimmable? > All pgs in the cluster have been deep scrubbed since my previous email and > I'm > not seeing any of that wasted space being recovered. > > Regards, > > LRT > > -----Original Message----- > From: Dan van der Ster <dvanders@xxxxxxxxx> > To: technology@xxxxxxxxxxxxxxxxxxxxx > Cc: Ceph Users <ceph-users@xxxxxxx>, Neha Ojha <nojha@xxxxxxxxxx> > Subject: Re: CephFS snaptrim bug? > Date: Thu, 24 Feb 2022 09:48:04 +0100 > > See https://tracker.ceph.com/issues/54396 > > I don't know how to tell the osds to rediscover those trimmed snaps. > Neha does that possible? > > Cheers, Dan > > On Thu, Feb 24, 2022 at 9:27 AM Dan van der Ster <dvanders@xxxxxxxxx> > wrote: > > > > Hi, > > > > I had a look at the code -- looks like there's a flaw in the logic: > > the snaptrim queue is cleared if osd_pg_max_concurrent_snap_trims = 0. > > > > I'll open a tracker and send a PR to restrict > > osd_pg_max_concurrent_snap_trims to >= 1. > > > > Cheers, Dan > > > > On Wed, Feb 23, 2022 at 9:44 PM Linkriver Technology > > <technology@xxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > Hello, > > > > > > I have upgraded our Ceph cluster from Nautilus to Octopus (15.2.15) > over the > > > weekend. The upgrade went well as far as I can tell. > > > > > > Earlier today, noticing that our CephFS data pool was approaching > capacity, I > > > removed some old CephFS snapshots (taken weekly at the root of the > filesystem), > > > keeping only the most recent one (created today, 2022-02-21). As > expected, a > > > good fraction of the PGs transitioned from active+clean to > active+clean+snaptrim > > > or active+clean+snaptrim_wait. In previous occasions when I removed a > snapshot > > > it took a few days for snaptrimming to complete. This would happen > without > > > noticeably impacting other workloads, and would also free up an > appreciable > > > amount of disk space. > > > > > > This time around, after a few hours of snaptrimming, users complained > of high IO > > > latency, and indeed Ceph reported "slow ops" on a number of OSDs and > on the > > > active MDS. I attributed this to the snaptrimming and decided to > reduce it by > > > initially setting osd_pg_max_concurrent_snap_trims to 1, which didn't > seem to > > > help much, so I then set it to 0, which had the surprising effect of > > > transitioning all PGs back to active+clean (is this intended?). I also > restarted > > > the MDS which seemed to be struggling. IO latency went back to normal > > > immediately. > > > > > > Outside of users' working hours, I decided to resume snaptrimming by > setting > > > osd_pg_max_concurrent_snap_trims back to 1. Much to my surprise, > nothing > > > happened. All PGs remained (and still remain at time of writing) in > the state > > > active+clean, even after restarting some of them. This definitely seems > > > abnormal, as I mentioned earlier, snaptrimming this FS previously > would take in > > > the order of multiple days. Moreover, if snaptrim were truly complete, > I would > > > expect pool usage to have dropped by appreciable amounts (at least a > dozen > > > terabytes), but that doesn't seem to be the case. > > > > > > A du on the CephFS root gives: > > > > > > # du -sh /mnt/pve/cephfs > > > 31T /mnt/pve/cephfs > > > > > > But: > > > > > > # ceph df > > > <snip> > > > --- POOLS --- > > > POOL ID PGS STORED OBJECTS USED %USED MAX > AVAIL > > > cephfs_data 7 512 43 TiB 190.83M 147 TiB 93.22 > 3.6 TiB > > > cephfs_metadata 8 32 89 GiB 694.60k 266 GiB 1.32 > 6.4 TiB > > > <snip> > > > > > > ceph pg dump reports a SNAPTRIMQ_LEN of 0 on all PGs. > > > > > > Did CephFS just leak a massive 12 TiB worth of objects...? It seems to > me that > > > the snaptrim operation did not complete at all. > > > > > > Perhaps relatedly: > > > > > > # ceph daemon mds.choi dump snaps > > > { > > > "last_created": 93, > > > "last_destroyed": 94, > > > "snaps": [ > > > { > > > "snapid": 93, > > > "ino": 1, > > > "stamp": "2022-02-21T00:00:01.245459+0800", > > > "name": "2022-02-21" > > > } > > > ] > > > } > > > > > > How can last_destroyed > last_created? The last snapshot to have been > taken on > > > this FS is indeed #93, and the removed snapshots were all created on > previous > > > weeks. > > > > > > Could someone shed some light please? Assuming that snaptrim didn't > run to > > > completion, how can I manually delete objects from now-removed > snapshots? I > > > believe this is what the Ceph documentation calls a "backwards scrub" > - but I > > > didn't find anything in the Ceph suite that can run such a scrub. This > pool is > > > filling up fast, I'll throw in some more OSDs for the moment to buy > some time, > > > but I certainly would appreciate your help! > > > > > > Happy to attach any logs or info you deem necessary. > > > > > > Regards, > > > > > > LRT > > > _______________________________________________ > > > 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 > _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
 |