zpool list vs df free space?

[Freddie Cash]

On Mon., Feb. 8, 2021, 12:27 p.m. joe mcguckin, <joe at via.net> wrote:

> df -h reports 66T available
>
> zpool list says 102T
>
> Why the discrepency?
>
> This is on a system with 7 16Tb drives configured as raidz2.
>
> Thanks,
>
> Joe
>
>
> Joe McGuckin
> ViaNet Communications
>
> joe at via.net
> 650-207-0372 cell
> 650-213-1302 office
> 650-969-2124 fax
>

"zpool list" shows the raw storage available on the pool, across all the
disks in the pool, minus some internal reserved storage.

"zfs list" shows the usable storage space after all the parity drives are
removed from the calculation.

"df" output can be misleading as it doesn't take into account compression
and reservations and things like that. It can give you an approximation of
available space, but it won't be as accurate as "zfs list".

For example, if you have 6x 2 TB drives configured as a single raidz2 vdev,
then:

zpool list: around 12 TB (6 drives x 2 TB)
zfs list: around 8 TB (4 data drives x 2 TB)
df: should be around 8 TB

Cheers,
Freddie

Typos due to smartphone keyboard.

>