On Mon, Dec 11, 2017 at 03:47:56PM +0100, Andreas Herrmann wrote: > Hi > > On 11.12.2017 14:17, Fabian Grünbichler wrote: > > On Mon, Dec 11, 2017 at 01:40:28PM +0100, Miguel González wrote: > >> 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? > > No! 'zpool list' will show what is used on disk. zfs list is totally > transparent to zpool layout. Have a look at 'zpool get all' for the ashift > setting.
I know. in most cases when people are surprised by their zvols taking up more space than expected, it is because they are using raidz and don't know about the interaction between ashift=12, raidz and small volblocksize. > > Example for raidz1 (4x 960GB SSDs): > root@foobar:~# zpool list > NAME SIZE ALLOC FREE EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT > zpool 3.41T 102G 3.31T - 8% 2% 1.00x ONLINE - > > root@foobar:~# zfs list > NAME USED AVAIL REFER MOUNTPOINT > zpool 237G 2.17T 140K /zpool > > zpool ALLOC is smaller than zfs USED in this example. Why? Try to unserstand > the difference between 'referenced' and 'used'. My volumes aren't sparse but > discard is used. your output is pretty worthless, as "REFER" only refers to the pool dataset, and not its children. I do know the difference between used and referenced, which is not (directly) related to discard at all. discard can obviously get your referenced value down ;) see the following for an example where a 10G volume takes more than 10G of space in 'zfs list' output: $ zfs list testpool -r -o name,used,referenced,volsize NAME USED REFER VOLSIZE testpool 14.3G 140K - testpool/test 14.3G 14.3G 10G $ zpool list testpool NAME SIZE ALLOC FREE EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT testpool 39.8G 19.7G 20.1G - 0% 49% 1.00x ONLINE - the only difference between a sparse and non-sparse zvol is whether refreservation is set, which affects the usedbyrefreservation value which in turn (might / probably will) affect the used value. no relation to discard at all. _______________________________________________ pve-user mailing list [email protected] https://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-user
