Specify which, if any, disk set your new component should belong to. Only disks and slices belonging to the specified disk set will be available, if you choose to use a disk set.

A disk set, is a set of shared disk drives containing logical volumes (RAID 0, RAID 1, RAID 5, transactional devices), state database replicas, hot spares, and soft partitions that can be shared exclusively, but not concurrently, by multiple identical hosts.