Hello:
You've actually posted this question to the Microsoft adCenter development forum, and unfortunately this is probably not the correct forum for your question.
I did take a quick look on MSDN for FILE_DEVICE_DISK though and came up with this topic that might be of some assistance.
http://msdn.microsoft.com/en-us/library/aa490468.aspxIf this is not the topic you need, I would suggest doing a search from here
http://msdn.microsoft.com/en-us/default.aspx to find the appropriate forum or documentation.
Best of luck
Bill Bledsoe
Operations Program Manager
SMB-A API, Tool Provider, Reseller