[zfs-discuss] How can I determine used and free space?
tk-zol at idpax.com
Sun Sep 13 18:01:09 EDT 2015
I've been using ZoL for the past 18 months and I like it but one of the
most confusing things to me is figuring out used and available space, in
particular when using multiple datasets under the same pool, with
So here's my actual situation:
4 x 3TB WD Red HDDs in a RAID-Z2 pool
# zpool list nas
NAME SIZE ALLOC FREE EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT
nas 10.9T 4.86T 6.01T - 3% 44% 1.00x ONLINE -
The 10.9T number above makes some sense given how HDD manufacturers rate
the space and some ZFS overhead/reserved space I assume. I understand
this is the raw space in the pool, before RAID-Z2.
This is where I start getting lost:
# zfs list -r nas
NAME USED AVAIL REFER MOUNTPOINT
nas 2.36T 2.75T 256K /nas
nas/archive 416G 2.75T 251G /nas/archive
nas/backup 591G 2.75T 255G /nas/backup
nas/data 11.5G 2.75T 9.66G /nas/data
nas/fast_backup 516M 2.75T 198K none
nas/fast_backup/home 516M 2.75T 507M none
nas/imp 147G 2.75T 147G /nas/imp
nas/media 1.22T 2.75T 1.06T /nas/media
I'm not sure how much space I actually used and how much I still have
available. Is it really that I only have USED + AVAIL = 5.11T usable
space out of the raw 10.9T? Any way I look at it doesn't seem to make a
lot of sense. Maybe it's the snapshots that I don't know how to take
Any good resources that can help me make sense of the used and available
space? Or maybe a kind soul could walk me through the numbers, please.
Thanks for your help.
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