My first question is about this metric: ceph_bluefs_read_prefetch_bytes and I want to know what operation is related to this metric? On Thu, Dec 3, 2020 at 7:49 PM Seena Fallah <seenafallah@xxxxxxxxx> wrote: > Hi all, > > When my cluster gets into a recovery state (adding new node) I see a huge > read throughput on its disks and it affects the latency! Disks are SSD and > they don't have a separate WAL/DB. > I'm using nautilus 14.2.14 and bluefs_buffered_io is false by default. > When this throughput came on my disk it will get too much high latency. > After I turned on bluefs_buffered_io another huge throughput around 1.2GB/s > came in and it against affect my latency but much less than the previous > one! (Graphs are attached and bluefs_buffered_io was turned on with ceph > tell injectargs at 13:41 also I have restarted the OSD at 13:16 because it > doesn't get better at the moment) > > I have four questions: > 1. What are they? I see the recovery speed is 20MB/s and client io on that > OSD is 10MB/s so what is this high throughput for?! > 2. How can I control this throughput? Because my disks don't support this > much throughput! > 3. I see a common issue here https://tracker.ceph.com/issues/36482 that I > think it's similar to my case. It was discussed about read_ahead, well > should I change the read_ahead_kb config of my disk to support this type of > request? I'm using the default value in ubuntu (128) > 4. Is there any tuning required that can help to turn off the > bluefs_buffered_io again? > > Configs I used for recovery: > osd max backfills = 1 > osd recovery max active = 1 > osd recovery op priority = 1 > osd recovery priority = 1 > osd recovery sleep ssd = 0.2 > > My OSD memory target is around 6GB. > > Thanks. > _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
 |