Proxmox ZFS pool: recurring disk access

[It's wednesday my dudes]

Hi,

I recently have set up a new Proxmox installation. The installation itself together with all VMs/containers are running from a SSD. Aditionally I have a ZFS mirror managed by Proxmox acting as a network storage. And for some reason the disks produce a disk access noise every 5 seconds. I googled and I found several things which might cause this (zfs sync etc) but so far I was not able to get rid of it. Also monitoring iotop doesn't show me an obvious cause. The weird thing is that I only noticed the noise after switching from actually way louder Seagate Exos drives to much quieter WD Reds. For some reason the Exos disks didn't seem to produce this noise even though they were way louder during access than the Reds. The noise isn't very loud but since the server is in my living room, it still bothers me. I am already thinking about changing the filesystem of the datastore to ext4 or btrfs since it is only used as a network share.

Does anyone here have some more ideas?

 

[Dunuin]

With ZFS async writes are first written to RAM and by default every 5 seconds (txg timeout) the data will be written from RAM to disk. But it should only do that when there is data that needs to be written, so you should check whats actually writing to your pool all the time. If you for example add a CIFS share to proxmox, proxmox will access that share every several seconds to check if the share is still available. And if you don't disabled the "atime" attribute ZFS will do a write for every read to update the atime metadata.
So first I would disabale the pools atime if your services don't rely on it (PBS for example does), so not every time a process reads a cached file in the ARC will cause an additional write operation.

 

[bearpaws]

I came here for the same reason. I have 8x2.5" drives as a ZFS pool and noticed it doing the same thing. Only when I shut down a few VE running does it stop the drives surging. There is no data being created or accessed just the VE sitting at idle. Any ideas why this is happening? IT will shorten the life of my drives and I would like to solve this issue.