Storage Area Network and SAN Protocols
Storage Area Network (SAN) is a high-speed network or subnetwork whose primary purpose is to transfer data between computer and storage systems. A storage device is a machine that contains nothing but a disk or disks for storing data. A SAN consists of a communication infrastructure, which provides physical connections; and a management layer, which organizes the connections, storage elements, and computer systems so that data transfer is secure and robust.
Typically, a storage area network is part of the overall network of computing resources for an enterprise. A storage area network is usually clustered in close proximity to other computing resources but may also extend to remote locations for backup and archival storage. SANs support disk mirroring, backup and restore, archival and retrieval of archived data, data migration from one storage device to another, and the sharing of data among different servers in a network. SANs can incorporate subnetworks with network-attached storage (NAS) systems.
There are a few SAN technologies available in today's implementations, such as IBM's optical fiber ESCON which is enhanced by FICON architecture, or the newer Fibre Channel technology. High speed Ethernet is also used in the storage Area Network for connection. SCSI and iSCSI are popular technologies used in the Storage Area Network.
A typical SAN architecture is diplayed as follows:
NAS: Network Attached Storage
Network Attached Storage (NAS) is a data storage mechanism that uses special devices connected directly to the network media. These devices are assigned an IP address and can then be accessed by clients via a server that acts as a gateway to the data, or in some cases allows the device to be accessed directly by the clients without an intermediary.NAS servers use small, specialized, and proprietary operating systems instead of general-purpose operating systems (OSs) such as the UNIX and Windows NT operating systems. Compared to the general-purpose OSs, NAS server OSs are smaller, faster, and optimized for the specialized task of file serving.
NAS servers support a variety of network file protocols such as Sun's Network File System (NFS) and Microsoft's Server Message Block / Common Internet File System (SMB/CIFS). NAS severs use open standard protocols, which allow them to interface with multiple types of client computers and operating systems.
