To add more disks to an aggregate in an existing Azure CVO instance, the supported method is to use ONTAP System Manager. This tool provides a user-friendly graphical interface for managing ONTAP features, including disk and aggregate management. Here's how:

Access ONTAP System Manager: Log into ONTAP System Manager on your Azure CVO instance.

Manage Disks and Aggregates: Navigate to the Storage or Aggregates section, where you can view existing aggregates and the disks assigned to them.

Add Disks to Aggregate: Select the aggregate you wish to expand and follow the prompts to add additional disks. This process may involve selecting disks from a pool of unassigned disks or reconfiguring existing disk resources.

For more detailed guidance on managing aggregates and disks in Azure CVO, refer to the specific section in the ONTAP System Manager documentation on disk and aggregate management: NetApp ONTAP System Manager.