Hi!
I've confirmed that the write IO to the metadata pool is coming form active MDSes.
I'm experiencing very poor write performance on clients and I would like to see if
there's anything I can do to optimise the performance.
Right now, I'm specifically focussing on speeding up this use case:
In CephFS mounted dir:
$ time unzip -q wordpress-seo.12.9.1.zip
real 0m47.596s
user 0m0.218s
sys 0m0.157s
On RBD mount:
$ time unzip -q wordpress-seo.12.9.1.zip
real 0m0.176s
user 0m0.131s
sys 0m0.045s
The difference is just too big. I'm having real trouble finding a good reference to
check my setup for bad configuration etc.
I have network bandwidth, RAM and CPU to spare, but I'm unsure on how to put it to
work to help my case.
Are there a lot of directories to be created from that zip file? I think
it boils down to the directory operations that need to be performed
synchrously. See
https://fosdem.org/2020/schedule/event/sds_ceph_async_directory_ops/
https://fosdem.org/2020/schedule/event/sds_ceph_async_directory_ops/attachm…
https://video.fosdem.org/2020/H.1308/sds_ceph_async_directory_ops.webm
Gr. Stefan
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