Hi Kenneth, > Any clues here? Thank you very much! > I assume you are running a Quincy version on your cluster. If so, from the Quincy release, mClock is set to be the default queuing scheduler. It was earlier set to the weighted priority queue scheduler (wpq). To maximize the effectiveness of the mClock algorithm, certain Ceph options are locked to specific values and one of them is osd_max_backfills which is locked to 1000. Another option which is locked to the same value is osd_recovery_max_active. With the mClock scheduler there are a couple of objectives from a user perspective, 1. Eliminate the need to set sleep throttles for various ops. Therefore, the Ceph config sleep options for various ops have been disabled or in other words locked to 0 in order to enable the mClock algorithm to work effectively. 2. Use mClock config profiles to hide the complexity of tuning various Ceph options You can read about mClock profiles and about the config options that are locked here <https://docs.ceph.com/en/quincy/rados/configuration/mclock-config-ref/>. Therefore, you can only limit the rate of backfills/recoveries using the mClock profiles. The 'high_client_ops' profile will allow the lowest recovery rate due to the way the QoS parameters are set up for the profile. Hopefully, the above should answer some if not all your questions. -Sridhar _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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