Hello Vladimir, I have noticed that our osd_mclock_max_capacity_iops_hdd > varies widely for OSDs on identical drives in identical > machines (from ~600 to ~2800). > The IOPS shouldn't vary widely if the drives are of similar age and running the same workloads. The osd_mclock_max_capacity_iops_hdd is determined using Ceph's osd bench during osd boot-up. From our testing on HDDs, the tool shows fairly consistent numbers (+/- a few 10s of IOPS) for a given HDD. For more details please see: https://docs.ceph.com/en/latest/rados/configuration/mclock-config-ref/#osd-capacity-determination-automated In your case, it would be good to take another look at the subset of HDDs showing degraded/lower IOPS performance and check if there are any underlying issues. You could run the osd bench against the affected osds as described in the link below or your preferred tool to get a better understanding: https://docs.ceph.com/en/latest/rados/configuration/mclock-config-ref/#benchmarking-test-steps-using-osd-bench > Is such great variation a problem? What effect on > performance does this have? > The mClock profiles use the IOPS capacity of each osd to allocate IOPS resources to ops like client, recovery, scrubs and so on. Therefore, a lower IOPS capacity will have an impact on these ops and therefore it would make sense to check the health of the HDDs that are showing lower than expected IOPS numbers. -Sridhar _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
 |