Hi, On 05/06/15 20:04, Mark Nelson wrote: > [...] > Out of curiosity, do you see excessive memory usage during > defragmentation? Last time I spoke to josef it sounded like it wasn't > particularly safe yet and could make the machine go OOM, especially if > there are lots of snapshots. > We have large amounts of memory (80GB) so we might have missed this. There was no problem with autodefrag though (we would have seen them because we had more limited amounts of free memory after OSD and VM being accounted for). Snapshots shouldn't be a problem for OSDs as it seems Ceph only maintains 2 at any given time. > I've also included some test results from emperor (ie quite old now) > showcasing how sequential read performance degrades on btrfs after > random writes are performed (on the 2nd tab you can see how even > writes are affected as well). Basically the first iteration of tests > look great up until random writes are done which causes excessive > fragmentation due to COW, then subsequent tests are quite bad compared > to initial BTRFS tests (and XFS). > > Your testing is thus quite interesting, especially if it means we can > reduce this effect. Keep it up! I'll have problems getting good results from inside VM as there is a constant load on this platform. Currently I'm limited to average results on total time spent accessing disks Best regards, Lionel _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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