Distributed File System

Network file shared can be reorganized into a logical namespace with Dfs. The Dfs volume is shared and accessed as a normal network share. The server where the data is stored becomes transparent. Dfs links point to other network shares using UNC names. Alternative paths provide fault tolerance and load balancing as shown in the following diagram. Dfs can be nested in that a link can point to another Dfs volume as shown in the following diagram.

	Dfs volume
	—	ÆÆÆ
	—	Æ		Another Dfs volume
			—	Æ
			—	Æ
	—	Æ
		î Alternate paths

NT servers can host Dfs volume and Windows 95 can be a Dfs client.

Dfs volumes can be hosted

• on a standalone server which becomes a potential single point of failure
• by the Active Directory where volume information is automatically replicated

Clients cache the destination of Dfs links. In the case of alternative paths, all paths are cached and then the client randomly picks one path. If the connection fails, another path is chosen. Some applications may fail as a result of this failover process.

Dfs servers should be within the same security boundary (i.e. same Active Directory), because the same security credentials are used to connect to all servers.