Hey admin colleagues

1) Do you run CEPH?
2) If so, do you have a SSD backed pool?
3) Do you use this pool for RBD images?

If you've answered all three with yes, do you run fstrim inside these RBD devices? (If yes please leave a comment so we can maybe reach out to you.) If you don't do it for a reason please leave a comment.

@ops yep, but also when I still had HDDs below, as fstrim on an rbd image reduces the number of objects in use - thin provisioning and stuff

Discard for the SSDs below is issued by bluestore already

@LittleFox the performance with HDDs here was too bad and HDDs to cheap.

Do you see major performance issues during the fstrim run on your VMs? How big is your cluster?

@ops the fstrim operation takes some time (at most around a minute per image), but that's mostly due to that only being half-automated and not run very frequently

For the few volumes with automated fstrim, I don't see any performance problems so far - but mostly use these volumes as k8s PVs, not disks for virtual machines, so they don't serve an OS but only the application itself

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@ops it's currently a 3 node / 4 OSD cluster, at it's biggest it had 6 nodes and 6 OSDs (but at that point all nodes were virtual servers rented from netcup)

All current nodes are k8s control plane and ceph control plane nodes, as well as ceph storage and k8s worker nodes - but runs quite well and fstrim never was any problem so far (had enough others)

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