iohyve add
Adds a new disk to the guest.
Usage: 'iohyve add <name> <size> [pool]' where <name> is the name of the guest, <size> is the size of the virtual block device in '16G' format where the capital G signifies gigabytes. If pool is specified, the disk gets added on that pool
I have not tested it but plan to in the next few days I get my lab up and running.