[OpenIndiana-discuss] 800GB in 6 discs - 460GB in raidz

[Timothy Coalson]

On Fri, Mar 24, 2017 at 5:43 PM, Harry Putnam <reader at newsguy.com> wrote:
>
> On the vm, I've created discs like so:
>
> 2 @  96G
> 2 @ 116G
> 2 @ 216G
>
> These have just over 2x variation in size, and you put them all in a
single raidz vdev, that is why your space is "missing" - it is just like
making a mirror out of a 96G disk and a 216G disk, which would have only
96G available and "lose" over 100G of space.  raidz doesn't do anything
magical for different-sized disks - it uses a slice from each device that
is equal to the *smallest* device in the vdev.

So, your raw space *before* parity or overhead (which is what "zpool list"
says) should be 6*96G = 576G.  Remove 1 device worth for raidz1 (5*96G =
480G), and a fudge factor for metadata overhead, and lands you at the 460G
that "zfs list" says about it.

Tim