Hi Mark, No, I wasn't familiar with that work. I am in fact comparing speed of recovery to maintenance work I did while the cluster was in Jewel; I haven't manually done anything to sleep settings, only adjusted max backfills OSD settings. New options that introduce arbitrary slowdown to recovery operations to preserve client performance would explain what I'm seeing! I'll have a tinker with adjusting those values (in my particular case client load on the cluster is very low and I don't have to honour any guarantees about client performance - getting back into HEALTH_OK asap is preferable).
Rich On 13/09/17 21:14, Mark Nelson wrote: > Hi Richard, > > Regarding recovery speed, have you looked through any of Neha's results on > recovery sleep testing earlier this summer? > > https://www.spinics.net/lists/ceph-devel/msg37665.html > > She tested bluestore and filestore under a couple of different scenarios. > The gist of it is that time to recover changes pretty dramatically depending > on the sleep setting. > > I don't recall if you said earlier, but are you comparing filestore and > bluestore recovery performance on the same version of ceph with the same > sleep settings? > > Mark > > On 09/12/2017 05:24 AM, Richard Hesketh wrote: >> Thanks for the links. That does seem to largely confirm that what I haven't >> horribly misunderstood anything and I've not been doing anything obviously >> wrong while converting my disks; there's no point specifying separate WAL/DB >> partitions if they're going to go on the same device, throw as much space as >> you have available at the DB partitions and they'll use all the space they >> can, and significantly reduced I/O on the DB/WAL device compared to >> Filestore is expected since bluestore's nixed the write amplification as >> much as possible. >> >> I'm still seeing much reduced recovery speed on my newly Bluestored cluster, >> but I guess that's a tuning issue rather than evidence of catastrophe. >> >> Rich
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