To see status of all the ZFS Pools, all arrays in ZFS is referred to as a pool.
zpool list
returns:
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT Pool1 43.5T 35.6T 7.94T - - 10% 81% 1.00x ONLINE /mnt freenas-boot 216G 5.08G 211G - - 0% 2% 1.00x ONLINE -