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Thursday, March 26, 2009

What is Storage Area Network

What is Storage Area Network

Knowing your computer is very vital sometimes it is not enough to only use tools like anti-spyware, anti-virus, registry cleaner etc. to fix some problems. This article lets you know what storage area network is.

SAN is a dedicated network that is separate from LANs and WANs. It is generally used to connect all the storage resources connected to various servers. It consists of a collection of SAN Hardware and SAN software; the hardware typically has high inter-connection rates between the various storage devices and the software manages, monitors and configures the SAN.

A storage area network is a high-speed special-purpose network that interconnects different kinds of data storage devices with associated data servers on behalf of a larger network of users. In computing, a storage area network is an architecture to attach remote computer storage devices such as disk arrays, tape libraries and optical jukeboxes)to servers in such a way that, to the operating system, the devices appear as locally attached. SANs are still uncommon outside larger enterprises.

By contrast to a SAN, network-attached storage uses file-based protocols such as NFS or SMB/CIFS where it is clear that the storage is remote, and computers request a portion of an abstract file rather than a disk block.

San Infracture

A SAN's architecture works in a way that makes all storage devices available to all servers on a LAN or WAN. As more storage devices are added to a SAN, they too will be accessible from any server in the larger network. In this case, the server merely acts as a pathway between the end user and the stored data.

Because stored data does not reside directly on any of a network's servers, server power is utilized for business applications, and network capacity is released to the end user.

A storage area network can use existing communication technology such as IBM's optical fiber ESCON or it may use the newer Fiber Channel technology. Some SAN system integrators liken it to the common storage bus in a personal computer that is shared by different kinds of storage devices such as a hard disk or a CD-ROM player.

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 system.

A SAN is made up of a number of fabric switches connected in a network. The most common form of SAN uses the Fiber Channel fabric protocol with Fiber Channel switches. Alternatively ISCSI could be used with IP switches.

Connected to the SAN will be one or more Disk array controllers and one or more servers. The SAN allows the storage space on the hard disks in the Disk array controllers to be shared amongst the servers.




Storage Area Types

Most storage networks use the SCSI protocol for communication between servers and disk drive devices. However, they do not use SCSI low-level physical interface as its bus topology is unsuitable for networking. To form a network, a mapping layer is used to other low-level protocols:

iFCP or SANoIP, mapping SCSI over Fibre Channel Protocol over IP.
iSCSI, mapping SCSI over TCP/IP.
iSER, mapping iSCSI over InfiniBand
HyperSCSI, mapping SCSI over Ethernet.
FICON mapping over Fiber Channel used by mainframe computers.
ATA over Ethernet, mapping ATA over Ethernet.
Fiber Channel over Ethernet

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