Creating mirrored volumes

Adding a plex to an existing unmirrored volume

Mirroring an unmirrored volume that uses mixed disk capacities

The unmirrored volume that you want to mirror might use disks of different capacities. For example, the volume might consist of several 36-GB disks and one 72-GB disk. Data ONTAP can mirror volumes that use mixed disk capacities by selecting disks that match the smallest capacity from a different disk pool. If there are not enough disks of that capacity in the disk pool, Data ONTAP selects a higher capacity disk and downsizes it.

See How Data ONTAP selects disks for the rules Data ONTAP uses to select disks.

Methods for adding a plex to an unmirrored volume

You can add a plex to an existing unmirrored volume using one of the following methods:

Let Data ONTAP select the disks used to mirror the volume.
Select the disks used to mirror the volume yourself.
Preview the disks Data ONTAP would use, then either use those disks or replace one or more of the disks with disks you choose.

Data ONTAP selects the disks

If Data ONTAP selects the disks used to mirror the volume, Data ONTAP adds the necessary number and type of disks from a separate pool. This is the easiest method of mirroring, but you do not have control over which disks Data ONTAP selects.

To mirror an existing volume by letting Data ONTAP select the disks used to mirror the volume, complete the following step.

Step	Action
1	At the prompt, enter the following command: vol mirror vol-name vol-name is the name of the volume you are mirroring (without the /vol/ prefix).

You select the disks

If you select the disks used to mirror the volume, you must ensure that you use the correct number of disks, the correct size of disks, and that the disks are in a different pool from the volume plex that you are mirroring.

To mirror an existing volume using disks you select, complete the following step.

Step	Action
1	At the prompt, enter the following command: vol mirror vol-name -d disk-list vol-name is the name of the volume you are mirroring (without the /vol/ prefix). disk-list consists of disk IDs of one or more available disks; separate multiple disks with a space.

You select the disks with assistance from Data ONTAP

Data ONTAP has a preview option that you can use to view what disks Data ONTAP would select if it were to mirror the volume.

To mirror an existing volume by previewing disks Data ONTAP would use in the form of a sample command, complete the following steps.

Step	Action
1	At the prompt, enter the following command: *vol mirror vol-name* -n** `-n` specifies to Data ONTAP not to create the mirrored volume, but show the disks that it would use if it did create the mirrored volume. vol-name is the name of the volume you are mirroring (without the /vol/ prefix). Result Data ONTAP returns a `vol` `mirror` command that specifies the necessary number and type of disks you can use to mirror the volume.
2	If you want to...	Then...
	Use the disks specified by Data ONTAP	At the prompt, enter the `vol` `mirror` command specified.
	Substitute other disks for one or more disks specified by Data ONTAP	At the prompt, enter the `vol mirror` command and substitute other disks for one or more of the disks specified.

Example

In this example, use the following command to preview the disks that Data ONTAP would use when mirroring the volA volume:

vol mirror volA -n

Data ONTAP returns the following command:

vol mirror volA -d 8.1 8.2 8.3