On Wed, Feb 12, 2020 at 6:08 PM Marc Roos <M.Roos@xxxxxxxxxxxxxxxxx> wrote: > > > > > > >> > >> Say I think my cephfs is slow when I rsync to it, slower than it > used > >> to be. First of all, I do not get why it reads so much data. I > assume > >> the file attributes need to come from the mds server, so the rsync > >> backup should mostly cause writes not? > >> > > > >Are you running one or multiple MDS? I've seen cases where the > >synchronization between the different MDS slow down rsync. > > One > > >The problem is that rsync creates and renames files a lot. When doing > >this with small files it can be very heavy for the MDS. > > > > Strange thing is that I did not have performance problems with luminous, > after upgrading to nautilus and enabling snapshots on a different tree > of the cephfs. Rsync is taking 10 hours more. > There is also another option, degrading performance on the source. > However it is impossible for me to verify this. > I have increased the mds_cache_memory_limit from 8GB to 16GB, see > what that brings. > how many snapshot are there ? > > > > >> I think it started being slow, after enabling snapshots on the file > >> system. > >> > >> - how can I determine if mds_cache_memory_limit = 8000000000 is > still > >> correct? > >> > >> - how can I test the mds performance from the command line, so I can > > >> experiment with cpu power configurations, and see if this brings a > >> significant change? > >> _______________________________________________ > >> 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
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