Storage Networking Glossary

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  • Arbitrated loop: A basic configuration of Fibre Channel networks in which up to 126 devices can share a single segment or loop, with one additional node left for linkage to a switch.
  • Escon: Mainframe channel devised by IBM that supports data rates of 200 Mbit/s over fiber. Depending on configuration, Escon can reach distances from about 3 to 10 kilometers, depending on fiber quality and product features.
  • FCIP: Fibre Channel over IP. A proposal advanced by the IETF's IP Storage Working Group for mapping Fibre Channel traffic directly onto IP, in order to facilitate WAN connectivity for SANs. More information is available at www.ietf.org
  • Fibre Channel: A network technology that sets up block-oriented streams of data over fiber at rates to 1 Gbit/s and distances up to 500 meters over multimode fiber and 1 km over singlemode fiber. Fiber Channel networks can be configured in switched or redundant loop topologies. Standards are governed by the American National Standards Institute (ANSI) and groups that support it, including the National Committee for Information Technology Standards (NCITS -- formerly X3).
  • Ficon: Mainframe channel devised by IBM that supports data rates of 1 Gbit/s at distances from about 10 to 20 kilometers over fiber.
  • SAN: Storage-area network. A network dedicated to providing and managing storage and backup for business or carrier networks. Because they're dedicated networks, SANs offer greater capacity and better performance than traditional storage and backup techniques, in which mainframes, servers, or other host computers are attached directly to disk and tape drives and managed via special software. Most SANs today are based on Fibre Channel switches and hubs, configured to occupy the "back end" portion of a network, behind the data center or server farm.
 
  • Host bus adapter: The card that fits into a computer, server, or mainframe that links it via Fibre Channel or SCSI to a storage device or storage network.
  • iSCSI: A proposal advanced by the IETF's IP Storage Working Group for mapping SCSI onto the TCP (transmission control protocol) in order to allow storage links to be extended greater distances over IP networks. For more detail, see www.ietf.org/internet-drafts
  • JBOD: Just a bunch of disks. Disk drives stacked together in a rack with a single attachment to a server or mainframe.
  • NAS: Network-attached storage. The setup in which a high-end server, typically a filer, is attached directly to the network that's making use of the backup, instead of to a separate SAN. SANs and NAS are often combined in today's storage networks.
  • RAID: Redundant Array of Inexpensive Disks. A technology in which data is stored in distributed fashion across multiple disk drives to achieve redundancy and improved data transfer rates.
  • SCSI: Small computer systems interface ("Scuzzy"). A short-range (25 meters or less) protocol designed to link host computers with storage devices such as disk drives. Typically implemented over copper cabling, SCSI is the most widely used and the oldest method of connecting computers to storage devices. Its distance limitations and lack of support for fiber helped launch the migration to SANs.
  • Storage director: A switch designed to link elements of a SAN or NAS across multiple sites. Storage directors are meant to act as a kind of switch of switches and are typically provided by makers of Fibre Channel switches.