Hi Tobias, On Thu, Apr 27, 2023 at 2:42 PM Tobias Hachmer <t.hachmer@xxxxxx> wrote: > > Hi sur5r, > > Am 4/27/23 um 10:33 schrieb Jakob Haufe: > > On Thu, 27 Apr 2023 09:07:10 +0200 > > Tobias Hachmer <t.hachmer@xxxxxx> wrote: > > > >> But we observed that max 50 snapshot are preserved. If a new snapshot is > >> created the oldest 51st is deleted. > >> > >> Is there a limit for maximum cephfs snapshots or maybe this is a bug? > > > > I've been wondering the same thing for about 6 months now and found the > > reason just yesterday. > > > > The snap-schedule mgr module has a hard limit on how many snapshots it > > preserves, see [1]. It's even documented at [2] in section > > "Limitations" near the end of the page. > > > > The commit[3] implementing this does not only not explain the reason > > for the number at all, it doesn't even mention the fact it implements > > this. > > Thanks. I've red the documentation, but it's not clear enough. I thought > "the retention list will be shortened to the newest 50 snapshots" will > just truncate the list and not delete the snapshots, effectively. > > So as you stated the max. number of snapshots is currently a hard limit. > > Can anyone clarify the reasons for this? If there's a big reason to hard > limit this it would be great to schedule snapshots more granular e.g. > mo-fr every two hours between 8am-6pm. This was done so that a particular directory does not eat up all the snapshots - there is a per directory limit on the number of snapshots controlled by mds_max_snaps_per_dir which defaults to 100 and therefore MAX_SNAPS_PER_PATH was chosen to be much lower than that. Also, at one point the kclient wasn't able to handle more than 400 snapshots (per file system), but we have come a long way from that and that is not a constraint right now. > > > Given the limitation is per directory, I'm currently trying this: > > > > / 1d 30d > > /foo 1h 48h > > /bar 1h 48h > > > > I forgot to activate the new schedules yesterday so I can't say whether > > it works as expected yet. > > Please let me know if this works. > > Thanks, > Tobias > _______________________________________________ > ceph-users mailing list -- ceph-users@xxxxxxx > To unsubscribe send an email to ceph-users-leave@xxxxxxx -- Cheers, Venky _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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