How do I expand the disk of a VM?

How do I expand the disk of a VM?

The following information uses Windows Server 2008 R2 Datacenter x64 Edition to describe the disk expansion procedure for a VM. 

1.  Verify that the VM does not have snapshots, contain multi-level image files, or use a volume provision mode of eager zeroed or lazy zeroed. 

 2. While the VM is running, change its disk size, for example, from 15 GB to 20 GB.

 3. Open Server Manager. 

     a. In the navigation pane, select Storage > Disk Management. 

     b. In the Disk Management pane, right-click the disk to be expanded, select Extend Volume, and then change the disk size as instructed. 

 4. If the disk is IDE, restart the VM for the expansion to take effect. If the disk is Virtio, skip this step. The expansion takes effect while the VM is running.