Known Issues with Running Windows Small Business Server 2008 in a Hyper-V Environment

Applies To: Windows SBS 2008

When you install Windows SBS 2008 in a virtual environment, some product features may not function as expected. This occurs because a virtual environment does not provide the full hardware functionality that some features require.

Before you implement virtualization in your Windows SBS 2008 network, you should first review and consider the following information.

General Issues

  • Hyper-V does not virtualize COM ports. As a result, if you attach a computer peripheral to a COM port on the physical system, that peripheral is not available to the guest operating systems.

  • Because Hyper-V does not virtualize COM ports, the Windows Server 2008 Fax server role is not supported in Hyper-V. For more information, see Knowledge Base article 958664 at the Microsoft Web site (

  • Hyper-V does not virtualize USB ports. Therefore, if you use an answer file to install your server, you must place a copy of the answer file on a virtual drive in the virtual machine.

  • USB support is not available in Hyper-V. However, you can take a USB disk drive offline in the parent partition, and then mount it “pass-through” to the IDE or iSCSE controller in a virtual machine. If you use this method to mount a disk drive to a virtual machine, you should consider the drive as an “internal” disk drive and should therefore not unplug the drive from the physical hardware.

    You can also use resource redirection during a Remote Desktop session to bring certain devices from your local computer into the virtual machine. For more information, see the following articles:

  • You might not be able to install Windows SBS 2008 in a virtual machine if you configured the virtual machine to use a different time zone than the parent partition. This can occur if the server that is installed in the virtual machine is a Windows SBS 2008 domain controller. For information about how to resolve this issue, see Knowledge Base article 956359 at the Microsoft Web site (

Server Backup and Restore Issues

  • You can configure an internal disk drive or a virtual hard drive (VHD) that is located on an internal disk drive as a server backup drive. To display internal disk drives in the Configure Server Backup Wizard, select the Show all drives check box in the wizard.

  • It is also possible to configure an external storage device as a server backup drive, but you should consider such a device as an internal drive. You should not disconnect an external storage device if you use the device to host a Hyper-V VHD or to host a virtual machine.

  • Do not back up or restore more than one partition at the same time. This causes a conflict when each instance of the backup or restore process tries to lock the Volume Shadow Copy Service (VSS) writer. For more information, see Knowledge Base article 958665 at the Microsoft Web site (

Additional Resources

For a list of other known issues, see the Hyper-V Release Notes at the Microsoft Web site (

For information about how to troubleshoot issues with Hyper-V, see “Troubleshooting Hyper-V” at the Microsoft Web site (