RaidZ2 capacity with 8x2TB

[James Harris]

I have 8x2TB hdd. I have created a single Z2 volume with all of the disks and the available capacity drops to 10GB rather than the expected 14GB approx. Am I reading this incorrectly?

Thank you.

 

[Stux]

Its exactly spot on.

http://wintelguy.com/zfs-calc.pl

Need to realise that TiB and TB is not the same.

http://wintelguy.com/tb2tib.html

Your 16TB of disk is actually about 14.5TiB of disk, and the simplistic calculation is that you should give up two disks for parity... so 12TB... Which is about 10.91TiB... and then there is abut 0.91TiB used for padding and slop... so 10TiB.

Which is nearly 10.9TB.

So, all up, you lose about 1.1TB extra to padding and slop over and above the 2 disks worth of parity.

slop is 1/32nd of your storage.