Hello,
Asking for help with an issue. Maybe someone has a clue about what's
going on.
Using ceph 15.2.17 on Proxmox 7.3. A big VM had a snapshot and I removed
it. A bit later, nearly half of the PGs of the pool entered snaptrim and
snaptrim_wait state, as expected. The problem is that such operations
ran extremely slow and client I/O was nearly nothing, so all VMs in the
cluster got stuck as they could not I/O to the storage. Taking and
removing big snapshots is a normal operation that we do often and this
is the first time I see this issue in any of my clusters.
Disks are all Samsung PM1733 and network is 25G. It gives us plenty of
performance for the use case and never had an issue with the hardware.
Both disk I/O and network I/O was very low. Still, client I/O seemed to
get queued forever. Disabling snaptrim (ceph osd set nosnaptrim) stops
any active snaptrim operation and client I/O resumes back to normal.
Enabling snaptrim again makes client I/O to almost halt again.
I've been playing with some settings:
ceph tell 'osd.*' injectargs '--osd-max-trimming-pgs 1'
ceph tell 'osd.*' injectargs '--osd-snap-trim-sleep 30'
ceph tell 'osd.*' injectargs '--osd-snap-trim-sleep-ssd 30'
ceph tell 'osd.*' injectargs '--osd-pg-max-concurrent-snap-trims 1'
None really seemed to help. Also tried restarting OSD services.
This cluster was upgraded from 14.2.x to 15.2.17 a couple of months. Is
there any setting that must be changed which may cause this problem?
I have scheduled a maintenance window, what should I look for to
diagnose this problem?
Any help is very appreciated. Thanks in advance.
Victor
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