Attach vdisk


Applies To: Windows 7, Windows Server 2008 R2, Windows Server 2012 R2, Windows Server 2012, Windows 8

Attaches (sometimes called “mounts” or “surfaces”) a virtual hard disk (VHD) so that it appears on the host computer as a local hard disk drive. If the VHD already has a disk partition and file system volume when you attach it, the volume inside the VHD is assigned a drive letter.


This command is only applicable to Windows 7 and Windows Server 2008 R2.

For an example of how this command can be used, see Examples.


attach vdisk [readonly] { [sd=<SDDL>] | [usefilesd] } [noerr]





Attaches the VHD as read-only. Any write operation returns an error.

sd=<SDDL string>

Sets the user filter on the VHD. The filter string must be in the Security Descriptor Definition Language (SDDL) format. By default the user filter allows access like on a physical disk.

SDDL strings can be complex, but in its simplest form, a security descriptor that protects access is known as a discretionary access control list (DACL). It is of the form: D:<dacl_flags><string_ace1><string_ace2>... <string_acen>

Common DACL flags are:

  • A – Allow access

  • D – Deny access

Common rights are:

  • GA – All access

  • GR – Read access

  • GW – Write access

Common user accounts are:

  • BA – Built in administrators

  • AU – Authenticated users

  • CO – Creator owner

  • WD - Everyone


D:P:(A;;GR;;;AU gives read-access to all authenticated users

D:P:(A;;GA;;;WD gives everyone full access


Specifies that the security descriptor on the .vhd file should be used on the VHD. If the Usefilesd parameter is not specified, the VHD will not have an explicit security descriptor unless it is specified with the Sd parameter.


Used for scripting only. When an error is encountered, DiskPart continues to process commands as if the error did not occur. Without this parameter, an error causes DiskPart to exit with an error code.


  • A VHD must be selected and detached for this operation to succeed. Use the select vdisk command to select a VHD and shift the focus to it.


To attach the selected VHD as read-only, type:

attach vdisk readonly

Additional references