Help me understand usable space

[wreedps]

I created a RAIDZ2 with 6x 4TB HGST. I says 21TB raw, I think, then 13TB usable after the RAIDZ2. Is that correct?

 

[Ericloewe]

21.7 TiB (21.7 * 2^40 bytes) or 24 TB (24 * 10^12 bytes) raw, without taking parity into account, and around 14 TiB usable after parity (used + available).

 

[wreedps]

Thanks!