When you add a disk or array LUN to a system running Data ONTAP, the disk or array LUN goes through several stages before it can be used by Data ONTAP to store data or parity information.
The process for making a disk available for use differs slightly from the process for making an array LUN available for use. Both processes are shown in the following diagram:
Data ONTAP can see the disk, but the disk is still unowned.
The disk is now a spare disk.
The disk is now in use by that aggregate. It could contain data or parity information.
Data ONTAP can see the array LUN, but the array LUN is still unowned.
The array LUN is now a spare array LUN.
The array LUN is now in use by that aggregate and is storing data.