Hi all,
I have the opposite problem as discussed in "slow down keys/s in recovery". I need to increase the number of objects in flight during rebalance. It is already all remapped PGs in state backfilling, but it looks like no more than 8 objects/sec are transferred per PG at a time. The pools sits on high-performance SSDs and could easily handle a transfer of 100 or more objects/sec simultaneously. Is there any way to increase the number of transfers/sec or simultaneous transfers? Increasing the options osd_max_backfills and osd_recovery_max_active has no effect.
Background: The pool in question (con-fs2-meta2) is the default data pool of a ceph fs, which stores exclusively the kind of meta data that goes into this pool. Storage consumption is reported as 0, but the number of objects is huge:
NAME ID USED %USED MAX AVAIL OBJECTS
con-fs2-meta1 12 216 MiB 0.02 933 GiB 13311115
con-fs2-meta2 13 0 B 0 933 GiB 118389897
con-fs2-data 14 698 TiB 72.15 270 TiB 286826739
Unfortunately, there were no recommendations on dimensioning PG numbers for this pool, so I used the same for con-fs2-meta1, and con-fs2-meta2. In hindsight, this was potentially a bad idea, the meta2 pool should have a much higher PG count or a much more aggressive recovery policy.
I now need to rebalance PGs on meta2 and it is going way too slow compared with the performance of the SSDs it is located on. In a way, I would like to keep the PG count where it is, but increase the recovery rate for this pool by a factor of 10. Please let me know what options I have.
Best regards,
=================
Frank Schilder
AIT Risø Campus
Bygning 109, rum S14
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