How disks and array LUNs become available for use

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:

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The process for disks includes the following actions:

The administrator physically installs the disk into a disk shelf.
Data ONTAP can see the disk, but the disk is still unowned.
If the system is configured to support disk autoassignment, Data ONTAP assigns ownership for the disk; otherwise, the administrator must assign ownership of the disk manually.
The disk is now a spare disk.
The administrator or Data ONTAP adds the disk to an aggregate.
The disk is now in use by that aggregate. It could contain data or parity information.

The process for array LUNs includes the following actions:

The storage array administrator creates the array LUN and makes it available to Data ONTAP.
Data ONTAP can see the array LUN, but the array LUN is still unowned.
The Data ONTAP administrator assigns ownership of the array LUN to a Data ONTAP system.
The array LUN is now a spare array LUN.
The Data ONTAP administrator adds the array LUN to an aggregate.
The array LUN is now in use by that aggregate and is storing data.