Hi, I had been testing some higher values with the osd_snap_trim_sleep variable to try and reduce the impact of removing RBD snapshots on our cluster and I have come across what I believe to be a possible unintended consequence. The value of the sleep seems to keep the lock on the PG open so that no other IO can use the PG whilst the snap removal operation is sleeping.
I had set the variable to 10s to completely minimise the impact as I had some multi TB snapshots to remove and noticed that suddenly all IO to the cluster had a latency of roughly 10s as well, all the dumped ops show waiting on PG for 10s as well. Is the osd_snap_trim_sleep variable only ever meant to be used up to say a max of 0.1s and this is a known side effect, or should the lock on the PG be removed so that normal IO can continue during the sleeps? Nick _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
