How to control disk selection from heterogeneous storage

When disks with different characteristics coexist on the same node, or when both disks and array LUNs are attached to the same node, the system has heterogeneous storage. When you create an aggregate from heterogeneous storage, you should take steps to ensure that Data ONTAP uses the disks you expect.

If your node has heterogeneous storage and you do not explicitly specify what type of disks to use, Data ONTAP uses the disk type (including array LUNs) with the highest number of available disks. When you create or add storage to an aggregate using heterogeneous storage, you should use one of the following methods to ensure that Data ONTAP selects the correct disks or disk types:

• Through disk attributes:
  • You can specify disk size by using the @size option.

    Disks within 20% of the specified size are selected.

  • You can specify disk speed by using the -R option.
  • You can specify disk type by using the -T option.
• Through an explicit disk list.

  You can list the names of specific disks you want to use.

• Through disk selection preview.

  You can use the -n option to identify which disks Data ONTAP selects automatically. If you are happy with the disks selected, you can proceed with automatic disk selection. Otherwise, you can use one of the previous methods to ensure that the correct disks are selected.