The Windows Azure Blob Service supports page blobs providing random read-write access to individual pages. The primary use case for a page blob is to store an NTFS-formatted virtual hard disk (VHD) that can be mounted in an instance of a Windows Azure role. The mounted NTFS drive is referred to as an Azure Drive.
An important limitation of an Azure Drive is that only one instance at a time can mount a VHD page blob as a writable Azure Drive. This means that two instances cannot write simultaneously to the same mounted Azure Drive, so it cannot be used to share real-time data between the two instances. The blob-leasing capability is used to ensure that the Azure Drive has exclusive write access to its backing VHD page blob until the Azure Drive is un-mounted.
The Blob Service supports read-only snapshots of blobs. Multiple instances can mount the same VHD snapshot simultaneously as a read-only Azure Drive. However, as a page blob snapshot backs the Azure...