> > >> >> 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. > >> 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 -- [email protected] To unsubscribe send an >> email to [email protected] >> > _______________________________________________ ceph-users mailing list -- [email protected] To unsubscribe send an email to [email protected]
