Hi Robert and Paul,
a quick update. I restarted all OSDs today to activate osd_op_queue_cut_off=high. I run
into a serious problem right after that. The standby-replay MDS daemons started missing
mon beacons and were killed by the mons:
ceph-01 journal: debug [...] log [INF] Standby daemon mds.ceph-12 is not responding,
Apparently, one also needs to set this on the MDSes:
ceph config set mds osd_op_queue_cut_off high
This also requires a restart to become active. After that, everything seems to work again.
The question that remains is:
Do I need to change this for any other daemon?
I will repeat the performance tests later and post results. On observation is, that an MDS
fail-over was a factor of 5-10 faster with the cut-off set to high.
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