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.
To limit the attachment of a Writable Volume to a specific computer, you can configure the Limit the attachment of user writables to specific computers setting when creating a Writable Volume. See Create a Writable Volume.
- A virtual machine can have only one Writable Volume attached to the virtual machine at a given time.
- A Writable Volume can be attached only to a single virtual machine at a given time.
- A Writable Volume must be enabled before it can be attached. See Enable a Writable Volume (2.x).
- Automatic Windows updates must be deactivated.
- 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.
- When App Volumes and VMware Dynamic Environment Manager are used together and a Dynamic Environment Manager condition references file or registry data on an App Volumes volume, the All AppStacks Attached trigger must be selected. This ensures that the Dynamic Environment Manager evaluates the condition after all volumes are attached.
For information about the All AppStacks Attached trigger, see Configure Triggered Tasks in the VMware Dynamic Environment Manager Administration Guide.
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 deactivated 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.