Just like a physical computer has storage, a virtual machine also has a storage volume associated with it. This is called the Root volume. You can choose to have additional storage as well. In the Volumes section you can view the details of your VM volumes, attach to, and detach volumes from your VMs, create volume templates and perform other tasks related to storage volumes.
A red circle next to a volume indicates that the volume is allocated, but not ready yet. A green circle indicates that the volume is ready to be attached, detached, downloaded and so on. as is applicable to that volume.
To view the details of a volume, select it from the list of volumes in the left pane.
ID: The unique identification code assigned by your service provider.
Type: The volume type. Root volume, Data volume
Zone: The CloudStack zone in which this volume resides.
Device ID: A unique system generated identifier for this volume.
Size: The storage space in GB. For example, 8 GB.
Created: The date and time the volume was created.
Account: The user who created this volume.
Domain: The domain assigned by your service provider.
The following section describes the menu items of the gear wheel icon. The menu shows the actions that you can perform. The menu items change depending on the Type (Root, Data etc.) and State (attached, detached) of the volume. For example, you cannot attach a volume that is already attached to a VM. In such a case, only the Detach Volume is available for that volume.
Select a volume. Move your cursor over the gear wheel icon. You see a list of actions that you can perform for the selected volume:
Click the Subscriptions tab to view the details of the subscription associated with the volume. The ID is the UUID of the subscription. The 'View Details' link displays the included entitlements. The name of the subscription links to the subscription in the Subscriptions page.
Attaching a volume: You can select a data volume and attach it to a VM. Click Attach Volume and specify the details. Accept the terms and conditions and click OK.
Downloading Volume: You can select a data volume and download it. Click Download Volume. Accept the terms and conditions and click OK.
Creating a Template: Click Create Template and specify the details for the template that you want to create from the volume. Accept the terms and conditions and click OK.
You can resize data disks. Depending on your need for data space, you can resize a data volume. Volumes within the disk offerings with the same storage tag can be resized. You can move a data volume from a static disk offering to a custom disk offering and specify the size.