I recently installed FreeNAS 8.x release and wanted to setup a per user quota. There is no way to set this up using the GUI front end – you can only setup a mount point quota at this time.

To setup a per user quota using the CLI, just login as root using your admin password, then issue the following commands:

zfs set userquota@USERNAME=10g SHARENAME
So in my case I had a /mnt/files filesystem, so I used:
zfs set userquota@thelibrarie=10g files

You can list the user quota
zfs list -o userquota@USERNAME SHARENAME

You can remove the user quota
zfs set userquota@USERNAME=none SHARENAME

View the current Input/Output statistics
zpool iostatzpool upgrade -v

View the current compression for all pools
zfs list -o compression