In part three of my continuing series, I cover Windows Azure Drives, an abstraction of Windows Azure Blob storage designed to provide a durable layer of storage with the same file I/O semantics of a local drive.
And here are the Handy Links for this episode:
Get your free 90-day Azure account Windows Azure Training Kit Blob Service Concepts Understanding Block Blobs and Page Blobs Windows Azure Drives White Paper
Get your free 90-day Azure account
Windows Azure Training Kit
Blob Service Concepts
Understanding Block Blobs and Page Blobs
Windows Azure Drives White Paper
great intro to CloudDrive ... one thing I wanted to ask, what if I have more than 1 instance ... only 1 instance will be able to mount this drive as writeable at a time. so how do I have a scale out application that many instances all want to write to a drive?
correct - drives employ a lease model, so can be mounted for write by only one VM/role instance at a time; snapshot can be used for read replicas. The White Paper quoted in the post provides a little insight into some patterns, including having a 'manager' role that oversees the allocation. It may be that each VM instance has its own drive and the 'manager' routes traffic - essentially a sharding pattern. Or, if it's not a heavy-write app, then perhaps all writes go through one instance (w/failover) - this was the original model for the Mongo on Azure implementation. Using SMB - see blogs.msdn.com/.../using-smb-to-share-a-windows-azure-drive-among-multiple-role-instances.aspx - is another option depending on the use case.