After clonging a vDisk and adding it back into the vDisk pool I was presented with the error
Management Interface: Vdisk File Access Denied
This was an easy fix. Check what account that the streasming service is using and makes sure that the appropirate permisson exists on the vDisk.
In my case it was the Network Service so adding in the Local Computer account and granting permission fixed the issue.
Permissions required are read\write although I simply gave the computer account full control.
Voila, issue resolved