You can assign Writable Volumes to a user, group, computer, or organizational unit (OU).

Note the following considerations and limitations when you assign and attach Writable Volumes:

  • When a Writable Volume is created for a user, it is assigned to the user immediately. When the volume is assigned to a group, it is created when a user belonging to the assigned group logs in to the machine.

  • A user can have more than one Writable Volume attached at the same time if the volume is OS-specific, or created for a computer with a specific prefix. For example, suppose that you create a Writable Volume for each of the following:

    • A Windows 7 machine

    • A Windows 10 machine

    • A computer with Win2012-dev prefix to its name

    • A computer with Win2012-test prefix to its name

    Then, when the user logs in to these different machines at the same time, each Writable Volume that is assigned to the specific machine is attached to the user at the same time.

  • A machine can have only one Writable Volume attached to it at a given point in time.

  • A Writable Volume must be enabled before it can be attached. See Enable a Writable Volume.

  • Automatic Windows updates must be disabled.

  • Detach the volume before performing any update to the OS.

  • Detach all Writable Volumes when performing any revert, recompose, or refresh of the virtual machines.


A user can also have multiple volumes attached to the same OS if there are two separate nodes and the user logs in to the desktop on both nodes.

Writable Volume Attachment Errors

If a Writable Volume that is assigned to a user or a computer does not attach correctly or if an assigned volume is running out of space, an error message is displayed and the user may have to restart the session.

The user may also see attachment errors when an assigned Writable Volume is disabled by the administrator or if the App Volumes agent is unable to access the volume due to permission issues, for example.

In such cases, the user can try to log in to a different VM and retry the operations. If the volume becomes available, the user can continue with the operations.

Similar errors are displayed if AppStacks are unable to get attached. See Assigning and Attaching AppStacks.