When disks with different characteristics coexist on the same storage system, the system is said to have a heterogeneous disk pool. When you add disks to an aggregate from a heterogeneous disk pool, you must explicitly select disks with the correct characteristics.
When you use the
aggr command to create a new aggregate or increase the size of an aggregate using a heterogeneous disk pool, use one of the following methods to ensure that the correct disks or disk types are selected:
- Specify the disk attributes you want to use:
- Use an explicit disk list.
You can list the ID numbers of specific disks you want to use.
- Use disk selection preview.
You can use the -n option to identify which disks Data ONTAP will select 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.
Note: For unplanned events such as a disk failures, which cause Data ONTAP to add another disk to a RAID group automatically, the best way to ensure that Data ONTAP will choose the best disk for any RAID group on your system is to always have at least one spare (and preferably two) available to match all disk types and sizes in use in your system.
