The computing industry has seen radical advancements in key system components over the past several years. Server and workstation motherboard processor MIPs have rocketed skyward and the cost per megabyte of hard disk drive storage has plummeted. With this, new client/server, network workgroup, and Internet applications have sprung forward with their users demanding and expecting to seamlessly use and share very large data bases with little or no delay. These data bases have expanded far beyond the traditional computer data to include video, audio, and graphical information. This information explosion has already begun to transform I/O and storage requirements as we have known them. 

The I/O and storage implementations most popular today are rapidly becoming ineffective and incapable of providing the bandwidth, throughput, flexibility, and reliability to meet the needs of these many new data-intensive applications. Although SCSI will still be practical for many applications for several years, its capabilities and growth path are limited.  

Fibre Channel possesses the characteristics not only to meet the demands of today, but as a total technology, to address the network and storage needs of mission-critical computing well into the next millenium. Fibre Channel is more than merely a new storage interconnect system. It is a complete interconnect architecture which complements the advancements in processor performance, and disk storage and networking functions. 

The table below highlights some of the more prominent capability differences between SCSI and Fibre Channel.  
 

At the physical level, Fibre Channel is a serial interface where SCSI is a parallel interface. With a serial interface, data can be transferred one bit after the other, over a single piece of medium (such as a copper wire), at the fastest speed possible for that medium. With a parallel interface, data is transferred over multiple pieces of the same medium (wires) simultaneously. Care must be taken to ensure that the data sent by the initiator over each individual wire arrives at the target device, at the far end of the cable, at the same time or data corruption will occur. Due to variations in the characteristics of each parallel wire, data travels through each piece at slightly different speeds. By keeping the data transfer rate of parallel SCSI relatively slow, and the cable length relatively short, corruption of data transferred through the SCSI bus can be effectively eliminated. Because Fibre Channel (with its serial data transfer method) is not subject to these restrictions, data can be transferred at much greater speed over much longer distances.  

Today Fibre Channel outperforms Ultra Wide SCSI in data transfer speed by a factor of 5 (utilizing two loops). Ultra-2 SCSI products, to be available in 1998, will allow 80 MB/s data transfers. However, the future road map for Fibre Channel calls for 400 MB/s data transfer speed on a single loop, 800 MB/s with dual loops, with even higher rates to follow. 

Fibre Channel's ability to attach storage devices along a single data path far exceeds SCSI, 126 to 15, a factor of 8. This connectivity is key to keeping pace with user's growing appetite for immediate gratification of their information needs. It also gives system designers the storage capacity scalability they need as their requirements grow in the future. 

The maximum Ultra SCSI bus length limitation of 3 meters (even less with 5 or more drives) has become a severe problem when physically configuring SCSI storage systems. Even with the use of SCSI extenders only short length extensions are possible. Fibre Channel unleashes system designers to configure campus-wide storage networks. Using copper media, cable lengths up to 30 meters between nodes can be used with lengths up to 10 kilometers possible via the use of fiber optic media. Daisy chaining many individual Fiber Channel subsystem cabinets is also possible with the only restriction being the total number of devices on a loop (126 limit). For example: with a Fibre Channel subsystem cabinet containing 7 disk drives, up to 16 cabinets can be serially attached. 

Fibre Channel's dual loop feature provides high resiliency for the storage data path and overall application processing environment. If one loop becomes unavailable, the loop is "self-healing" with the second loop taking over. This storage-related redundancy is complemented with dual-ported disk drives, dual power supplies and cooling fans, hot-swappable disk drives, power supplies and cooling fans, and the use of RAID and ECC (Error Correcting Code) SIMMs. 

Fibre Channel's data transfer rates, connectivity, and allowable cable distance opens up a world of opportunity for business solution development. Applications like imaging, video editing, video on demand, and other multimedia applications have tremendous needs for high bandwidth and storage capacity that is well suited to Fiber Channel. Fibre Channel technology opens the door for meeting the scalability needs of Internet file servers. Traditional on-line transaction processing systems, which transfer high volumes of small blocks of data, can now go to a new dimension in performance. Three dimensional design workstations (CAD/CAE) which need to manipulate large blocks of data can gain a raw speed boost via the use of Fibre Channel. Mission-critical backup and disaster recovery capabilities for banking, reservation systems, and on-line information systems now have both a distance and speed advantage through Fibre Channel. Disk storage can now be safely placed over six miles away from the host and still be on-line. Also, through a Fibre Channel strategy, remote mirroring of information can be implemented. 

Fibre Channel technology creates a new system design paradigm due to its combination of increased speed, distance, and connectivity. It will enable existing applications to run faster and will facilitate the development of new applications that were not previously possible. Today's applications that are prime candidates for Fiber Channel solutions include Internet/Intranet, data warehousing, video on demand, video editing and broadcasting, on-line services, medical imaging, and interactive telecommunications.