問題現象 - Hyper snapshot刪除後avhd殘留
問題成因 - 需要使用介面上的shut down來清除刪除的Snapshot，由guest os內shot down無法刪除avhd
解決方案 - 使用介面上的shut down來清除刪除的Snapshot
參考資訊 -
What other important considerations should I be aware of when using snapshots?

Keep the following considerations in mind, especially if you plan to use snapshots on a virtual machine in a production environment:

• The presence of a virtual machine snapshot reduces the disk performance of the virtual machine.
• When you delete a snapshot, the .avhd files that store the snapshot data remain in the storage location until the virtual machine is shut down, turned off, or put into a saved state. As a result, when you delete a snapshot, you will need to put the production virtual machine into one of those states at some point to be able to complete the safe removal of the snapshot.
• We do not recommend using snapshots on virtual machines that provide time-sensitive services, or when performance or the availability of storage space is critical.

參考

Hyper-V Virtual Machine Snapshots: FAQ

http://technet.microsoft.com/zh-tw/library/dd560637(WS.10).aspx