# Space-used differ on a raid-z2 pool dataset vs exact same dataset on a mirror pool (same settings)...



## chris123 (Feb 22, 2019)

Hi

Running FreeNAS 11.2 and found it strange that a dataset created on a raid-z2 pool (4 disks, 4TB each, seagate) is taking up more space than the exact same dataset using same settings (at least when comparing zfs get all pool/dataset, see attachment) on a mirror pool (2 disks, 4 TB each, seagate). gzip9 and recordsize 16k. 

raid-z2 pool: du -h -d0 → 46GB
                     du -hA -d0 → 73GB

mirror pool:  du -h -d0 → 32GB
                     du -hA -d0 → 73GB

Is it supposed to be like that?

I posted this question on the freenas forum as well but I didn't get any explanation, so I'm hoping someone here might have an answer.

Thanks


----------

