Home | Contents | Help   Raidhelp     Interfaces: Fibre Channel Fibre Channel Arbitrated Loop (FC-AL) is an ANSI-standard serial connectivity technology designed for data and communication intensive storage applications such as data warehousing, data mining, on-line transaction processing (OLTP), Internet/intranet access, and film/video/broadcast implementations. Fibre Channel transfers data at 200 MB/sec in a dual-loop configuration or at 100 MB/sec in redundant mode, with future products expected to push performance to 400 MB/sec. Bus lengths reach 30 metres using copper cables and 10 kilometres with fibre-optic cabling. The maximum number of devices per loop is 126. Fibre Channel standards include specifications for mapping SCSI, HIPPI, IP, ATM, and other channel and network protocols making it an ideal interface choice for connecting RAID arrays built from large Fibre Channel or SCSI drives to networks and servers. As the legacy support for other protocols makes FC-AL also part of the SCSI family as well as many others, it is perfectly placed to extend the life of traditional SCSI disks rather than simply introduce a new standard that requires new equipment. Any existing SCSI drives or arrays can be given a performance boost in a FC-AL environment without destroying any existing data or array set-ups. Fibre Channel simply uses a different physical/electrical interface, in this case a serial connection rather than the traditional parallel interface as used in single-ended SCSI.  Existing SCSI based storage and peripherals may be linked to a Fibre Channel environment using a SCSI bridge. The Fibre Channel standard also allows for a variety of connections and cabling media including single-mode fibre, multi-mode fibre, and four types of copper cabling, or even a combination of all media and connector types in a single environment. Changing between different media types is done simply with the use of with the use of Gigabit Interface Converters (GBIC) or interface converter. A GBIC can can easily change the media interface from copper to fibre for example by simply plugging in the copper cable on one side and the fibre cable on the other.  A RAID controller with Ultra2 SCSI drive channels and a Fibre Channel host channel uses the best of both worlds - extremely fast and competitively priced hard drives on a multi-threaded I/O bus, and a high performance flexible network/host connection that is more than capable of transferring the full bandwidth of the combined drive throughput. The controller itself provides the functions of a basic SCSI Bridge without any other equipment required for the transition between media types. It is important to note whether the controller will transmit the data to all attached hosts using standard SCSI command sets and protocols over fibre, or translate the signal to another protocol providing direct network attached storage (NAS) functions.  Related topics: The Interface Decision SCSI Interface Performance Expectations     Raidhelp   RAIDhelp© Copyright 1999-2004 Antony Kershaw