Today, I'll start by taking a look at Windows Azure Drives. Specifically, I'll explain how to programmatically determine the driver letter for a Windows Azure Drive. (I'll assume you've read the getting started post I wrote a couple of weeks ago.) Simply put, a Windows Azure drive acts as a local NTFS volume that is mounted on the server's file system and that is accessible to code running in a role. The data written to a Windows Azure drive is stored in a page blob defined within the Windows Azure Blob service, and cached on the local file system.

He shows how he's set up his instance with two drives and how, with a bit of PHP code, he could grab the value from the "X_DRIVES" environment variable, split it out and loop to find the drive you're looking for. His example code puts a simple text file on the drive and then reads it back out.