Testing FreeNAS

[HollyB]

Hi,
I would like to learn FreeNas. I create two 10 GB drives for testing. I create a ZFS volume with the two HDs using mirroring and not deduplication options. Now I have a volume that has 7.8 GiB as size. So I loose around 22%.
Is this Ok?
Can I have more information about?

 

[paleoN]

From the FAQ:

because FreeNAS™ reserves 2GB at the beginning of each disk for striped swap space.