Storage Area Networks (SANs): The SAN architecture physically and logically separates storage from servers.
It uses a Block I/O architecture. Storage resources are contained in stand-alone SAN storage subsystems and tape devices that are accessed over a dedicated network. Storage sits “behind” the server, as in DAS, but the storage can be accessed from any host attached to the SAN. Multiple hosts can be configured to access the same storage devices, allowing servers and storage to scale independently.