VMware View 4.5 introduced a disposable disk that can be configured on a per pool basis. The disposable disk is a separate disk for the GuestOS paging and system temporary files. VMware View Manager deletes the disposable files, including the whole VMDK, every time a linked clone is powered off. I have written more about Disposable disks in this article: VMware View 4.5 Storage Tiering explained.
The drive letter used by the disposable disk is automatically assigned by VMware View Manager using the next available (unused) drive letter. This behaviour cannot be changed and in some cases this drive letter could coincide with a network share that is mapped via user logon script or AD group policies. In this case you normally would have to re-architect your drive mappings, but in some cases this could be very trick if the application using the mapped drive is a long term established or legacy application.
As today the only possible way to specify a driver letter is to change the pool setting manually in ADAM.
If you use ADSI Edit or ldp and browse to “DC=vdi,DC=vmware,DC=int” the objects relating to Desktop Pools will be in some of the entries in OU=Server Groups. Selected the CN= that contains the desktop pool you want to change and edit the attribute pae-SVIVmPersistentDiskSpec.
Remove the entry that contains DiskUsage=SystemDisposable and add a new entry. The new entry should be:
Now you only need to recompose your desktop pool and the virtual machine’s disposable disk will be using the drive letter specified by you. I do believe VMware is working on a fix to allow administrators to select the drive letter to be assigned to disposable disks, just like we do today with Persistent disks (User Data Disk).