Difference between SAN and NAS

SAN (Storage Area Network)	NAS (Network Attached Storage)
A SAN commonly utilizes Fibre Channel , iSCSI, FCoE interconnects	A NAS typically makes Ethernet and TCP/IP connection
Drive would be Local drive For example E:/ , F:/, G:/	Drive appears are a remote drive e.g. \\234.10.10.34\remoteServer\name
As it is Local drive so you can do all operations on the drive same as your local drive. E.g. Format drive	A good example of this is with Microsoft Windows network drives.  If you map a network drive in windows you get a drive letter, but windows shows this drive as a network drive.  Only the one user has access to it, and windows will not let you use this drive for many functions.(e.g. You can’t format)
Protocols – iSCSI, FC, FCOE	Protocols – NFS / CIFS
How does SAN work ? (BLOCK Level) When using a SAN you are operating at the block level.  Let me explain with example, This means when you want to access ‘jassiPic.jpg’ This means the client machine can’t simply ask for ‘jassiPic.jpg’.  The client machine needs to actually tell the SAN where on the volume the file is.  The operating system will send a message to the SAN asking for specific blocks on the file system.  For example, if the picture is stored in blocks 9994 - 9998, then the client system would ask for blocks 9994 - 9998, the SAN would read those blocks, then send them over the network.  The SAN does not know what it is reading, it is simply following orders	How does NAS  work ? (File Level) When working with NAS storage, the client machine operates at the file level.  This means when you want to access ‘jassiPic.jpg’ your computer sends a message the NAS over the network asking for mycoolpicture.jpg, then the NAS responds by sending the file
File System managed by servers	File System managed by NAS head unit. For example EMC and Hitachi needs NAS Heads to work as NAS (File level). NetApp provides unified solution means same storage box can act as SAN or NAS without need of a NAS head
A NAS identifies data by file name and byte offsets, transfers file data or file meta-data (file's owner, permissions, creation data, etc.), and handles security, user authentication, file locking	A SAN addresses data by disk block number and transfers raw disk blocks