On 02/03/17 19:54, David Turner wrote: > Our current solution in Hammer involves a daemon monitoring the > cluster load and setting the osd_snap_trim_sleep accordingly between 0 > and 0.35 which does a good job of preventing IO blocking and help us > to clear out the snap_trim_q each day. These settings not being > injectable in Jewel would negate an option of using variable settings > throughout the day. Are you sure they're not injectable? [Almost?] everything says "unchangable", but it takes effect anyway. I have tested "snap_trim_sleep", and as Nick has pointed out, it seems to cause rather than prevent blocks (and I found the sweet spot is 0, but he seems to think it's higher). I can reproduce that very reliably using injectargs (+5 to sleep means +5s block length), so (unless luck can happen in such extreme ways, or somehow only part of the effect changed) they are changable.
I'm using Jewel. So I am now using: osd_pg_max_concurrent_snap_trims=1 osd_snap_trim_sleep=0
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