yes, but i cant unmount the disk :<
# mount
freenas-boot/ROOT/default on / (zfs, local, noatime, nfsv4acls)
devfs on /dev (devfs, local, multilabel)
tmpfs on /etc (tmpfs, local)
tmpfs on /mnt (tmpfs, local)
tmpfs on /var (tmpfs, local)
freenas-boot/grub on /boot/grub (zfs, local, noatime, nfsv4acls)
backup_2x250 on /mnt/backup_2x250 (zfs, NFS exported, local, nfsv4acls)
backup_2x250/jails on /mnt/backup_2x250/jails (zfs, local, nfsv4acls)
backup_2x250/.system on /var/db/system (zfs, local, nfsv4acls)
backup_2x250/.system/cores on /var/db/system/cores (zfs, local, nfsv4acls)
backup_2x250/.system/samba4 on /var/db/system/samba4 (zfs, local, nfsv4acls)
backup_2x250/.system/syslog-4c6211b89a3046dfbe28e409c4a02537 on /var/db/system/syslog-4c6211b89a3046dfbe28e409c4a02537 (zfs, local, nfsv4acls)
backup_2x250/.system/rrd-4c6211b89a3046dfbe28e409c4a02537 on /var/db/system/rrd-4c6211b89a3046dfbe28e409c4a02537 (zfs, local, nfsv4acls)
backup_2x250/.system/configs-4c6211b89a3046dfbe28e409c4a02537 on /var/db/system/configs-4c6211b89a3046dfbe28e409c4a02537 (zfs, local, nfsv4acls)
linprocfs on /compat/linux/proc (linprocfs, local)