ZFS: use ZVOLs to store VMs (by default)

[harvie]

Hello,
i have ZFS storage configured in my PVE and when i create new LXC CT it automatically creates ZFS subvolume, which is really great. But when i create new KVM VM it creates raw image on the ZFS filesystem rather than ZVOL. This results in huge performance penalty and is approach that is highly not reccomended by ZFS developers. They suggest to use ZVOLs instead of big binary files to store disk images and similar stuff on ZFS. Is there way to do this through web interface so i don't have to create ZVOLs using SSH commandline and then add them as raw device manually?

I think it really makes sense to use ZFS ZVOLs for VMs, same way it makes sense to use ZFS subvolumes fot CTs. That way the ZFS would be cool replacement for LVM. Also it's really bad idea to store regular image files on ZFS.

 

[dietmar]

But when i create new KVM VM it creates raw image on the ZFS filesystem rather than ZVOL.

This is not true. We use ZVOL if you use the zfs storage plugin. Maybe you selected the wrong storage?

 

[harvie]

It's strange. It works now for me. But i've been trying this few updates ago. Is that recently added feature? I am pretty sure that i've used ZFS storage for that. Maybe i screwed something up back then...

 

[dietmar]

Is that recently added feature?

No, it always worked that way...