Hi,
I'm working on a new implementation of a new erasure code. During my
development, I began testing the performance of my code & ceph LRC
plugin vs jerasure.
When setting up a cluster with failure domain being only leaf cells
(osd) I saw the expected behaviour - recovery of LRC is faster than
jerasure.
Next I divided my cluster into 5 hosts, each containing 8 osds, and
placed each local group under a different host (using ruleset-steps).
Jerasure still had osd as failure domain. At this point I noticed that
LRC has slower recovery. I've tried a configuration of k=4, l=3 and
total of 9 shards.
I don't think it's collisions in crush, since it shouldn't have such a
heavy effect.
My suspicion is some sort of a throttle. I've tried to set the following:
osd recovery max active = 500
osd recovery op priority = 32
But I didn't see any significant improvement.
Can you think of a reason LRC would recover slower than jerasure when
it's constrained to domains as I've described?
Thanks,
Oleg
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