Interesting article published at the end of last year:
The article does a deep dive into the Storage Architecture of Azure. It’s a shame this feature seems to on ice for Microsoft (by customer demand for sure, since SQL Azure is getting all the fans), since the architecture has a lot of potential in scalability and reliability.
The three main layers are:
- Front-End Layer, responsible to authenticate, authorize and route each requests to a partition server.
- Partition Layer, responsible to load balance partitions across a server farm.
- Distributed (and replicated) File System (DFS), responsible for storing bits on disk and to replicate it.
The article goes through a request lifecycle, how failures at different layers are addressed, how Azure Fault & Upgrade domains relate to this architecture and how partitioning is automatically handled.
This gives you a very good overview of Azure Storage behind the scene!