The "rmdir" command takes seconds. However, the resulting storm of activity on the cluster AFTER the deletion is bringing our cluster down completely. The blocked requests count goes into the thousands. The individual OSD processes begin taking up all of the memory that they can grab which causes the kernel to kill them off, which further throws the cluster into disarray due to down/out OSDs. It takes multiple DAYS to completely recover from deleting 1 snapshot and constant monitoring to make sure OSDs come up and stay up after they get killed for eating too much memory. This is a serious issue that we have been fighting with for over a month now. The obvious solution is to destroy the cephfs entirely, but that would mean we have to then recover about 40TB of data, which could take a very long time and we'd prefer not to do that. For example: 2521055 ceph 20 0 16.908g 0.013t 29172 S 28.4 10.6 36:39.52 ceph-osd 2507582 ceph 20 0 22.919g 0.019t 42076 S 17.6 15.5 58:48.00 ceph-osd 2501393 ceph 20 0 22.024g 0.018t 39648 S 14.7 14.9 79:05.28 ceph-osd 2547090 ceph 20 0 21.316g 0.017t 26584 S 7.8 14.0 18:14.76 ceph-osd 2455703 ceph 20 0 20.872g 0.017t 19784 S 4.9 13.8 111:02.06 ceph-osd 246368 ceph 20 0 22.657g 0.018t 37416 S 3.9 14.5 462:31.79 ceph-osd On Tue, Oct 10, 2017 at 12:03 AM, Yan, Zheng <ukernel@xxxxxxxxx> wrote: > On Tue, Oct 10, 2017 at 12:13 AM, Wyllys Ingersoll > <wyllys.ingersoll@xxxxxxxxxxxxxx> wrote: >> We have a cluster (10.2.9 based) with a cephfs filesytem that has >> 4800+ snapshots. We want to delete most of the very old ones to get it >> to a more manageable number (such as 0). However, deleting even 1 >> snapshot right now takes up to a full 24 hours due to their age and >> size. It would literally take 13 years to delete all of them at the >> current pace. >> >> Here is one snapshot directory statistics: >> >> # file: cephfs/.snap/snapshot.2017-02-24_22_17_01-1487992621 >> ceph.dir.entries="3" >> ceph.dir.files="0" >> ceph.dir.rbytes="30500769204664" >> ceph.dir.rctime="1504695439.09966088000" >> ceph.dir.rentries="7802785" >> ceph.dir.rfiles="7758691" >> ceph.dir.rsubdirs="44094" >> ceph.dir.subdirs="3" >> >> There is a bug filed with details here: http://tracker.ceph.com/issues/21412 >> >> Im wondering if there is a faster, undocumented, "backdoor" way to >> clean up our snapshot mess without destroying the entire filesystem >> and recreating it. > > deleting snapshot in cephfs is a simple operation, it should complete > in seconds. something must go wrong If 'rmdir .snap/xxx' tooks hours. > please set debug_mds to 10, retry deleting a snapshot and send us the > log. (it's better to stop all other fs activities while deleting > snapshot) > > Regards > Yan, Zheng > >> >> -Wyllys Ingersoll >> Keeper Technology, LLC >> -- >> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
