Adding disks to mirrored volumes

Rules to follow when adding disks

When you add disks to a mirrored volume, you must follow these rules:

The number of disks you add must be an even number and equally divided between the two plexes.
The disks that you add to each plex must come from different disk pools.
The disks you add must have equivalent bytes per sector (bps) size.
The disks you add must have capacity equal to or greater than those disks in the plexes.
Note
If you add a larger capacity disk, Data ONTAP downsizes the larger disk to an equivalent size of the disks in the volume.

Methods for adding disks

You can add disks to mirrored volumes using the following methods:

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

Data ONTAP selects the disks

To add disks to a mirrored volume, complete the following step.

Step	Action
1	At the prompt, enter the following command: *vol add vol-name* ndisks[@disk-size]** vol-name is the name of the volume to which you are adding disks. ndisks is the number of disks to use. Adding new disks will fail if the number of disks is an odd number. disk-size is a number that specifies the disk size to use, in gigabytes. You must have half of the ndisks available disks of the size you specify in one disk pool and half of the ndisks available disks of the size you specify in another disk pool if you use this option. Note If you use the `disk-size` option, first determine the size of spare disks in the disk pools using the `vol` `status` `-r` command.

Step

Action

At the prompt, enter the following command:

vol add vol-name ndisks[@disk-size]

vol-name is the name of the volume to which you are adding disks.

ndisks is the number of disks to use. Adding new disks will fail if the number of disks is an odd number.

disk-size is a number that specifies the disk size to use, in gigabytes. You must have half of the ndisks available disks of the size you specify in one disk pool and half of the ndisks available disks of the size you specify in another disk pool if you use this option.

Note
If you use the disk-size option, first determine the size of spare disks in the disk pools using the vol status -r command.

You select the disks

If you select the new disks to add to the mirrored volume, you must ensure that you use the correct number of disks, the correct size of disks, the disks have the same checksum compatibility, and that the disks you add to one volume plex are in a different pool from the disks you add to the other volume plex.

To add new disks to a mirrored volume using disks you select, complete the following steps.

Step	Action
1	Enter the following command to list available spare disks: vol status -r
2	Using the rules listed in Rules to follow when adding disks, choose the spare disks you want to add.
3	At the prompt, enter the following command: vol add vol-name -d disk-list -d disk-list vol-name is the name of the volume to which you are adding disks (without the /vol/ prefix). disk-list consists of disk IDs of one or more available disks; separate multiple disks with a space. Both `-d` options must be used, one for each plex. Data ONTAP automatically assigns the disks to the appropriate plex. Note Specifying only one disk set using the `-d` option will fail. Example In this example, use the following command to add disk 3.1 to one plex and disk 8.1 to the other plex of the volD mirrored volume: vol add volD -d 6.1 -d 8.1

Step

Action

Enter the following command to list available spare disks:

vol status -r

Using the rules listed in Rules to follow when adding disks, choose the spare disks you want to add.

At the prompt, enter the following command:

vol add vol-name -d disk-list -d disk-list

vol-name is the name of the volume to which you are adding disks (without the /vol/ prefix).

disk-list consists of disk IDs of one or more available disks; separate multiple disks with a space. Both -d options must be used, one for each plex. Data ONTAP automatically assigns the disks to the appropriate plex.

Note
Specifying only one disk set using the -d option will fail.

Example

In this example, use the following command to add disk 3.1 to one plex and disk 8.1 to the other plex of the volD mirrored volume:

vol add volD -d 6.1 -d 8.1

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 add new disks to the volume.

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

Step	Action
1	At the prompt, enter the following command: *vol add vol-name* -n ndisks[@disk-size]** vol-name is the name of the mirrored volume to which you are adding disks (without the /vol/ prefix). ndisks is the number of disks to use. Adding new disks will fail if the number of disks is an odd number. disk-size is a number that specifies the disk size to use, in gigabytes. You must have half of the ndisks available disks of the size you specify in one disk pool and half of the ndisks available disks of the size you specify in another disk pool if you use this option. Note If you use the `disk-size` option, first determine the size of spare disks in the disk pools using the `vol` `status` `-r` command. Result Data ONTAP returns a `vol` `add` command that specifies the disks it would add to each plex of the mirrored volume.
2	If you want to...	Then...
	Use the disks specified by Data ONTAP	At the system prompt, enter the `vol` `add` command specified.
	Substitute other disks for one or more disks specified by Data ONTAP	At the system prompt, enter the `vol add` 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 adding two new 36 GB disks to the volA mirrored volume:

vol add volA -n 2@36

Data ONTAP returns the following command:

vol add volA -d 6.4 -d 8.6

Adding disks to mirrored volumes

Rules to follow when adding disks

Methods for adding disks

Data ONTAP selects the disks

You select the disks

Example

You select the disks with assistance from Data ONTAP

Result

Example