Hi, Quoting Stefan Kooman (stefan@bit.nl):
Hi,
After the upgrade to 13.2.8 deep-scrub has a big impact on client IO: loads of SLOW_OPS and high latency. We hardly ever had SLOW_OPS, but since the upgrade the impact is so big that we even have OSDs marking each other out (OSD op thread timeout) multiple times during the scrub window. Plenty of CPU / RAM / IOPS left, hardly any load on these OSD servers. Has there anything changed in this release that can explain this behaviour?
Besides this the impact of rebalance is very severe as well. With only the balancer remapping a couple of PGs at a time there are loads of (MDS_)SLOW_OPS. This morning the cephfs metadata pool got rebalanced ... and that triggered a lot of SLOW_OPS. One particular OSD was pegged at 1000% CPU for more than half an hour (not doing that much IO): that's 10 cores going full throttle! After a restart this issue was gone.
We can now also trigger SLOW_OPS on a bunch of OSDs when we do a "rbd du -p $POOL", something that has never been an issue. The images in the rbd pools have the following features enabled: layering, exclusive-lock, object-map, fast-diff, deep-flatten. Has there anything changed in 13.2.8 that affects these kind of operations? Gr. Stefan -- | BIT BV https://www.bit.nl/ Kamer van Koophandel 09090351 | GPG: 0xD14839C6 +31 318 648 688 / info@bit.nl