NAS Vs SAN
NAS devices are storage appliances big, single purpose servers that you plug into your network.
These appliances perform one task, and they perform it well: They serve files very fast.
The difference between how a NAS appliance and a SAN function is subtle.
NAS is a defined product that sits between your application server and your file system.
SAN is a defined architecture that sits between your file system and your underlying physical storage.