[SOLVED] ZFS use and available storage space

[MikeNick]

Hi,

I have a zfs pool made up of two raidz2s with 6 4TB drives each. I'm new to ZFS, so I apologize if the terminology is incorrect.
When I look a it from the left panel of the proxmox homepage it says it's 80% full because each image seems to be allocated >4TB.
When I look at it from <server>/disks/zfs it says it's ~25% full which is much closer to the truth (based on the amount of data loaded onto it).

The problem seems to be related to AVAIL:
(I realize that zpool was probably a bad name for the pool)

root@server:~# zfs list -o space
NAME                 AVAIL   USED  USEDSNAP  USEDDS  USEDREFRESERV  USEDCHILD
zpool                4.48T  20.8T        0B    153K             0B      20.8T
zpool/vm-100-disk-0  4.48T  26.1G        0B   25.7G           423M         0B
zpool/vm-101-disk-0  4.51T  1.59T        0B   1.57T          27.6G         0B
zpool/vm-102-disk-0  4.50T  65.3G        0B   47.9G          17.4G         0B
zpool/vm-102-disk-1  4.51T  39.2G        0B   6.42G          32.7G         0B
zpool/vm-102-disk-2  19.0T  19.1T        0B   4.57T          14.5T         0B

Anyway, is there a way to reclaim the extra TB from the images that are only a few dozen gigs?

Thanks,
Mike

 

[LnxBil]

You have not enabled sparse, so you "use" a lot of space for space reservation. If you would use sparse, your would have any USEDREFRESERV.

Please run:

zfs get -t filesystem,volume refreservation

 

[MikeNick]

Ahh, thanks.
I set the refreservation to none and got the usage down significantly. There's still a good deal of overhead, but it is more inline with what I'd expect for various ashift and block size types of things compared with a half dozen 64GB volumes have used up all of my 20TB pool.