Microsoft KB Archive/937366

= The host computer stops responding when you try to copy a file to a virtual hard disk that you mounted by using the VHDMount utility in Virtual Server 2005 R2 SP1 =

Article ID: 937366

Article Last Modified on 6/12/2007

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APPLIES TO


 * Microsoft Virtual Server 2005 R2 Standard Edition
 * Microsoft Virtual Server 2005 R2 Enterprise Edition

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SYMPTOMS
Consider the following scenario:
 * You install Microsoft Virtual Server 2005 R2 Service Pack 1 (SP1).
 * You create a virtual machine that has a dynamic virtual hard disk (VHD).
 * You use the VHDMount utility (Vhdmount.exe) to mount the VHD as a virtual disk in the Windows operating system.
 * You use the Vhdmount /p command at a command prompt to mount the VHD.
 * You copy a file to the VHD. The file that you copy is larger than the physical hard disk on the computer.

In this scenario, the host computer may stop responding (hang).



CAUSE
This issue occurs because the VHD and the file system on the host computer do not recognize that the physical hard disk is full.



WORKAROUND
To prevent this issue, verify that the physical disk has sufficient hard disk space to mount the VHD and to perform the required operations. If the VHD is mounted with an undo disk (This is the default setting.), you must have free hard disk space that is double the size of the VHD.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
The VHD communicates at the driver level to the file system on the host computer. Therefore, the VHD does not recognize that the physical hard disk is full. Additionally, the file system on the host computer does not recognize that the physical hard disk is full. The file system interprets the write failure as disk corruption.

Note When this issue occurs, the file system on the host computer does not correctly release the VHD file handle when you cancel the copy operation, and then you unmount the VHD. Therefore, you must restart the host computer.

Keywords: kbtshoot kbprb KB937366

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