Microsoft Hyper-V Server SAN policy is set to automatically mount volumes on startup

Applies to: Hyper-V Server 2008Microsoft Hyper-V Server 2008 R2


When Microsoft Hyper-V Server is started, it automatically tries to mount all the volumes that are connected to the server. These volumes include volumes on local disks and Storage Area Network (SAN) logical unit numbers (LUNs).


The default SAN policy in Microsoft Hyper-V Server is designed for ease of use. The policy enables the user to get started with a deployment immediately, without having to mount additional volumes that are stored on a SAN. However, you may not want to use this default setting in some environments.


To resolve this problem use one of the following methods to change the default SAN policy.

Method 1:Use diskpart

  1. Log on to the system with administrative rights.
  2. Click Start, click Run, type cmd, and then press ENTER.
  3. In the command line window, type diskpart, and then press ENTER.
  4. Type SAN, and then press ENTER. This command will return the current set SAN policy.
  5. Type SAN POLICY = OfflineShared, and then press ENTER. The SAN policy is now set not to automatically mount SAN hosted volumes.
  6. Type exit, and then press ENTER.

Method 2: Set the SAN policy in the Unattended setup file for automated deployment scenarios

The following code will change the SAN policy not to automatically mount SAN hosted volumes.

Method 3: Use the Virtual Disk Service (VDS) programming interface

For more information, visit the following Microsoft Web site:

More Information

The SAN policy is defined within the VDS environment of the system and is represented by the following values:
  • VDS_SP_UNKNOWN = 0x0
  • VDS_SP_ONLINE = 0x1
  • VDS_SP_OFFLINE = 0x3
For more information, visit the following Microsoft Web site: On Windows Server 2008 Enterprise and Windows Server 2008 Datacenter, the default SAN policy is VDS_SP_OFFLINE_SHARED. On all other Windows Server 2008 editions, the default SAN policy is VDS_SP_ONLINE.