[PVE-User] zfs 0.7 no discard

Gianni Milo gianni.milo22 at gmail.com
Tue Jul 9 21:52:12 CEST 2019

Haven't moved to zfs 0.8 but you could have similar results by enabling
compression on zfs and by periodically executing fstrim (linux) or sdelete
(windows) inside VMs to reclaim unused space ?

On Linux VMs, adding "discard" in fstab mount options (ext4) may have
similar results as when executing fstrim.

On Windows 10/2012+ VMs, defrag command can be used to perform free space

Make sure you enable "discard" option on the VM disk options tab (which you
seem to have done already).

Check this article on wiki as well...


On Tue, 9 Jul 2019 at 09:49, Mark Adams <mark at openvs.co.uk> wrote:

> Hi All,
> Currently having an issue on a few servers where more space is being "used"
> in the host (zfs), than is actually being used inside the VM. Discard is
> enabled, but zfs 0.7 does not have support for it.
> zfs 0.8 has brought in discard support, so I was wondering if anyone else
> has upgraded to it to resolve this kind of issue?
> I realise it's in proxmox 6, but I don't want to go there until it's out of
> beta.
> Any comments appreciated!
> Cheers,
> Mark
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