NAS (Network Attached Storage) provides file-level data access to a heterogeneous group of clients. It utilizes file-based protocols such as NFS (Network File System) and SMB (Server Message Block) to share data over a LAN. SAN (Storage Area Network) provides block-level network access to storage. It connects servers to data storage devices (disk arrays, tape libraries) so the devices appear to the operating system as locally attached devices. SANs utilize block protocols including Fibre Channel (FC), Fibre Channel over Ethernet (FCoE), and iSCSI to transmit SCSI commands.

Storage Networking Industry Association (SNIA). SNIA Dictionary of Storage Networking Terminology. Definitions for "Network Attached Storage (NAS)" and "Storage Area Network (SAN)".

Quote: "NAS: A term used to describe a storage device... providing file access services... typically using NFS or CIFS/SMB."

Quote: "SAN: A network whose primary purpose is the transfer of data between computer systems and storage elements... [typically] Block I/O."

Cisco Systems. "Storage Area Networking Solutions Design Guide." Cisco Validated Design.

Context: confirm FCoE and FC as primary SAN protocols for block storage transport.

NetApp. "What is NAS? | Network Attached Storage." NetApp Official Documentation.

Context: "NAS... allows multiple users... to retrieve data from centralized disk capacity... using protocols like NFS and SMB."

NetApp. "What is a SAN? | Storage Area Network." NetApp Official Documentation.

Context: "SANs are primarily used to access data storage devices... accessible to servers so that the devices appear like locally attached operating system devices... [Protocols include] FCP, iSCSI, FCoE."