Missing space on ZFS Pool

[lipskioff]

Hi!
I've build my first TrueNAS machine for video editing based on Dell T320 with SSD for system and 8x WD RED Pro 4TB disks combined into RaidZ2 pool but TrueNAS reports only 20TiB of available space with all 8 disk used for the pool. What could I have done wrong? Why is it 20TB instead of 24TB?

 

[JohnDigital]

This is actually right on the money as you lose 8TB off the top for parity. So you start with 24TB (not true), you lose some for slop space and the fact that you didnt actually even start with 32TB (you started with 29.103832 TB), etc.. Check out this calculator. Your result is right on at 19.977778 TiB.