You can use the Add Disks to Aggregate dialog box to add spare disks to an existing aggregate to increase its size, so that it can provide more storage space to its contained volumes.
Steps
1.
From the Home tab, double-click the appropriate storage system.
2.
In the navigation pane, click Storage > Disks.
3.
Select one or more spare disks that you want to add to the aggregate and click Add to Aggregate.
4.
Select the aggregate to which you want to add the spare disks and click Add.
