Specifies the number of disks you want to use.
When you create a new aggregate or traditional volume, you must have at least two disks available if you have selected RAID Level 4 protection. You must have at least three disks available if you are using double-parity RAID protection.
Note: To keep you from accidentally using the last spare, the maximum number of disks you can select is the number of available disks minus one spare. To select all the available disks, use the command-line interface.
You can add additional disks later, but you cannot remove disks after they have been added.