You can use clay codes(1). This reads less data for reconstruction. 1- https://docs.ceph.com/en/latest/rados/operations/erasure-code-clay/ On Fri, Jun 25, 2021 at 2:50 PM Andrej Filipcic <andrej.filipcic@ijs.si> wrote:

Hi,

on a large cluster with ~1600 OSDs, 60 servers and using 16+3 erasure coded pools, the recovery after OSD failure (HDD) is quite slow. Typical values are at 4GB/s with 125 ops/s and 32MB object sizes, which then takes 6-8 hours, during that time the pgs are degraded. I tried to speed it up with

osd advanced osd_max_backfills 32 osd advanced osd_recovery_max_active 10 osd advanced osd_recovery_op_priority 63 osd advanced osd_recovery_sleep_hdd 0.000000

which at least kept the iops/s at a constant level. The recovery does not seem to be cpu or memory bound. Is there any way to speed it up? While testing the recovery on replicated pools, it reached 50GB/s.

In contrast, replacing the failed drive with a new one and re-adding the OSD is quite fast, with 1GB/s recovery rate of misplaced pgs, or ~120MB/s average HDD write speed, which is not very far from HDD throughput.

Regards, Andrej

-- _____________________________________________________________ prof. dr. Andrej Filipcic, E-mail: Andrej.Filipcic@ijs.si Department of Experimental High Energy Physics - F9 Jozef Stefan Institute, Jamova 39, P.o.Box 3000 SI-1001 Ljubljana, Slovenia Tel.: +386-1-477-3674 Fax: +386-1-425-7074 ------------------------------------------------------------- _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io