root@vm-host:~# zpool status -v
  pool: storage
 state: ONLINE
  scan: scrub repaired 0 in 17h55m with 0 errors on Sun Aug 21 17:55:17 2016
config:

	NAME        STATE     READ WRITE CKSUM
	storage     ONLINE       0     0     0
	  raidz2-0  ONLINE       0     0     0
	    sdd     ONLINE       0     0     0
	    sdc     ONLINE       0     0     0
	    sdf     ONLINE       0     0     0
	    sde     ONLINE       0     0     0
	    sda     ONLINE       0     0     0
	    sdb     ONLINE       0     0     0
	cache
	  sdh2      ONLINE       0     0     0

errors: No known data errors
root@vm-host:~# zpool add storage log /dev/sdh1
cannot add to 'storage': one or more devices is currently unavailable