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Unformatted text preview: Storage area network From Wikipedia, the free encyclopedia Jump to: navigation , search In computing , a storage area network ( SAN ) 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. Although cost and complexity is dropping, as of 2007 , SANs are still uncommon outside larger enterprises . By contrast to a SAN, network-attached storage (NAS) 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. Contents [ hide ] 1 Network types 2 Storage sharing 3 SAN-NAS hybrid 4 Benefits 5 SAN infrastructure 6 Compatibility 7 SANs at home 8 SANs in the Media and Entertainment 9 Storage virtualization and SANs 10 See also 11 References 12 External links o 12.1 SAN Software Articles and White Papers [ edit ] Network 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 (e.g. cables), as its bus topology is unsuitable for networking. To form a network, a mapping layer is used to other low-level protocols: &quot; iFCP &quot;  or &quot;SANoIP&quot;  mapping SCSI over Fibre Channel Protocol (FCP) over IP. iSCSI , mapping SCSI over TCP/IP . HyperSCSI , mapping SCSI over Ethernet . FICON mapping over Fibre Channel (used by mainframe computers ). ATA over Ethernet , mapping ATA over Ethernet. SCSI and/or TCP/IP mapping over InfiniBand (IB). Fibre Channel over Ethernet ( http://open-fcoe.org/ ) [ edit ] Storage sharing The driving force for the SAN market is rapid growth of highly transactional data that require high speed, block-level access to the hard drives (such as data from email servers, databases, and high usage file servers). Historically, enterprises were first creating &quot;islands&quot; of high performance SCSI disk arrays . Each island was dedicated to a different application and visible as a number of &quot;virtual hard drives&quot; (or LUNs ). SAN essentially enables connecting those storage islands using a high-speed network. However, an operating system still sees a SAN as a collection of LUNs and is supposed to maintain its own file systems on them. Still, the local file systems, which cannot be shared among multiple hosts, are the most reliable and most widely used. If two independent local file systems resided on a shared LUN, they would be unaware of the fact, would have no means of cache synchronization and eventually would corrupt each other. Thus, sharing data between computers through a SAN requires advanced solutions, such as SAN file systems or clustered computing ....
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This note was uploaded on 03/26/2011 for the course IT 101 taught by Professor Dontknow during the Spring '07 term at Northern Virginia.
- Spring '07