You can expand mirrored vedev based arrays, but you do it by adding vdevs, so you are looking at adding TWO drives at a time. You can also (sorta) expand Z1 arrays by adding whole additional vdevs, or by replacing each drive in the array one at a time.
You can expand mirrored vedev based arrays, but you do it by adding vdevs, so you are looking at adding TWO drives at a time. You can also (sorta) expand Z1 arrays by adding whole additional vdevs, or by replacing each drive in the array one at a time.