Computers

NAS is an abbreviation for - network attached storage. Accessing the storage array is performed using a standard data network (usually Giga Ethernet).

SAN is an abbreviation for - Storage Area Network, meaning, having a fast dedicated network, which operates mostly on FC protocol, enabling a connection between the storage system and servers, and often backup libraries.

When to use NAS and when to use SAN?

The most common scenario for using NAS, is when an organization needs to serve files, scalability and a rich feature set, that could include features such as replication (ability to copy data between two storage arrays for redundancy and survivability) snapshots, and more.

SAN enables very good performance, and therefore is mainly used as internal disks on servers that do not provide much in terms of performance or capacity. Another good reason to use on SAN is to build clusters of servers that require shared access to the same storage.

What protocols are used for NAS?
In the world of Linux, the most commonly used protocol is NFS protocol veteran (and excellent) with advanced features such as locks on the area bits and more.

With windows, the most commonly used protocol is CIFS or SMB protocol from IBM that has undergone many changes by the members at microsoft

Protocols on SAN?
Most common protocol is fiber channel protocol thin, usually implemented in optical fiber switched configuration, and is intended to enable high-rate connectivity, as well as redundancy and survivability of the network.

Today you can find types of fiber channel spanned the IP, ETHERNET and more, and in order to reduce communication costs, or to overcome the large geographical distances.

Another protocol used SAN is iSCSI. This protocol allows very inexpensive connectivity by Giga Ethernet.

Which are the most prominent manufacturers in the market?
Of course, each major hardware manufacturers has solutions: IBM, HP, HDS, and more. There are the Storage only manufacturers such as EMC and NETAPP.

Also of note, a number of server-based solutions such as NEXENTA, OPEN-E, freenas, open filer.
These solutions can be used as a cheaper alternative to solutions of major players, of course, the usual prices of open source.J