[PVE-User] sparse and compression

[Fabian Grünbichler]

On Mon, Dec 11, 2017 at 03:23:34PM +0100, Miguel González wrote:
> 
> >>  Can I change a zpool to sparse on the fly or do I need to turn off all
> >> VMs before doing so?
> > 
> > sparse will only affect newly created volumes. you can "convert" sparse
> > volumes to fully reserved ones and vice versa manually though.
> > 
> 
> how can I convert manually from non-sparse to sparse? Creating a new
> zpool and copy disk with dd? Or any other easier way?

(un)set the reservations appropriately. like I said, "sparse" is
entirely virtual for ZFS, the only difference is whether the full size
is reserved upon creation or not.

> >>  Why a virtual disk shows as 60G when originally It was 36 Gb in raw format?
> >>
> >>  NAME                       USED  AVAIL  REFER  MOUNTPOINT
> >>  rpool/data/vm-102-disk-1  60.0G  51.3G  20.9G  -
> > 
> > wild guess - you are using raidz of some kind? ashift is set to 12 /
> > auto-detected?
> 
> Yes, raid1
> 
> Thanks for your promptly reply!

raid1 (aka mirror)? or raidZ-1 ? those are two very different things ;)