ZFS and LVM

[taich]

I run a proxmox 7 server with a ZFS storage. I recently installed oracle linux as a VM on it and since then I have problems with io-delay.
As soon as I start this VM io-delay goes up to 80-90%. The server is neatly slow.

I moved the disk to another storage (NFS) and io-delay went down to 1%.

Since oracle linux uses LVM I think that ZFS and LVM wont do well thogether.
Or is there another reason for this behaviour?

 

[Dunuin]

In general LVM ontop of ZFS should run fine. I guess it should be something else. You should check whats writing that much inside the VM. Maybe iostat/htop/iotop might help to find it out.

 

[taich]

There is nothing fancy. The VM writes every 1-2 seconds about 10-20k.
May be there are some ZFS parameters to set.

 

[Dunuin]

What filesystem is Oracle Linux using ontop of the LVs?

 

[LnxBil]

What filesystem is Oracle Linux using ontop of the LVs?

Depends on the version. XFS, EXT4 and BTRFS are possible.

I use Oracle Linux a lot (5-8) and did not experience such behaviour on my 6-disk ZFS SSD pool.

 

[taich]

My oracle linux 8 uses XFS and I have only one ZFS disk.
And I checked it again, as soon as I move the oracle disk to ZFS io-delay goes up to 80%.
NFS and local dir do not show this behavior.