S T 3 9 1 7 5 F C SEAGATE Native| Translation ------+-----+-----+----- Form 3.5"/HH Cylinders | | | Capacity form/unform 9170/ MB Heads | | | Seek time / track / ms Sector/track | | | Controller FC-AL FIBRE CHANNEL Precompensation Cache/Buffer KB Landing Zone Data transfer rate MB/S int Bytes/Sector 512 MB/S ext Recording method operating | non-operating -------------+-------------- Supply voltage Temperature *C | Power: sleep W Humidity % | standby W Altitude km | idle W Shock g | seek W Rotation RPM read/write W Acoustic dBA spin-up W ECC Bit MTBF h Warranty Month Lift/Lock/Park YES Certificates ********************************************************************** G E N E R A L ********************************************************************** SEAGATE FC-AL INTERFACE An Overview of Fibre Channel --------------------------- Introduction ------------ Everyone has accepted the fact that we have moved into the Age of Information. In this paradigm information itself is a commodity, and therefore there is great value in its efficient disbursement. Unfortunately, industry has placed greater value in creating information, than distributing it. We often hear about new machines which are capable of performing prodigious calculation at the blink of an eye. New reports of ever faster computers are commonplace. Sharing this information, however, has become a priority only recently. It seems that although we have moved into the Age of Information, one of our biggest challenges is to efficiently distribute the information for everyone to use. Luckily, a viable solution is at hand. Conceived and supported by such industry giants as IBM, Hewlett-Packard, and Sun Microsystems, the Fibre Channel is aimed at providing an inexpensive, flexible and very high-speed communications system. Most of the popular network implementations today can claim to have any two of these elements. Since Fibre Channel encompasses all three, it has everything necessary to become a resounding success. Not the Network Fibre Channel has significant advantages over common networks. The first difference is speed. The fastest network implementations today support transfer data at a little over 100 megabits per second. For smaller data files, where a single computer is directly communicating with a file server, such speeds are adequate. However, for realtime video and sound, or systems where two machines must operate on common data even 200 megabits per second is hopelessly inadequate. Fiber Channel provides significantly higher rates, from 10 to 250 times faster than a typical Local Area Network (LAN). In fact, Fibre Channel can transfer data at speeds exceeding 100 megabytes, or 800 megabits, per second. This speed is sufficient to allow transfer of a 1024x768 image with 24-bit color at 30 frame per second, and CD- quality digital sound. This overcomes the bandwidth limitation, which is probably the most serious impediment for LAN performance. As the number of computers communicating on a common network increases, the amount of data packets increases accordingly. This is because data on a LAN is common to all computers on that network. The software must decide if a particular message is relevant for a particular machine. When several machines are communicating with one another, every other machine on the network must contend with all of the messages. As the number of messages increases, the load for the entire system is increased. Fiber channel is a switched system. Much like a telephone system, a connection is established between only the parties that need to communicate. These parties can share the entire bandwidth of Fibre Channel, since they do not have to contend with messages not relevant to their communication. LANs attempt to compensate for this by increasing the transfer speed, which places an even greater burden on the software. Since all protocol for Fibre Channel is handled by the hardware, the software overhead is minimal. Fibre Channel also supports full parallelism, so if greater capacity is needed, more lines can be added. The common analogy for showing the advantages of parallelism is the effect of doubling the number of lanes on a freeway instead of doubling the speed limit. The physical distance between computers is another limiting factor for conventional LANs. Ethernet cables usually have a limit of 1000 feet between machines whereas Fibre Channel can support a link between two up to 10 kilometers apart. Finally, Fibre Channel is not software intensive. All of the essential functions are handled by hardware, freeing the computer's processor to attend to the application at hand. Even the error correction for transmitted data is handled by the Fibre Channel hardware. In standard LANs this requires precious processor resources. Advantages for Computing ------------------------ The obvious advantage for Fibre Channel is to facilitate communication between machines. Several workstations clustered together already surpass the speed and capacity of a VAX, and begin to rival the power of a super computer, at a much lower cost. The power of concurrent processing is awesome. For example, a single neuron inside our brain is much less complex, and operates far slower than a common 286 processor. However, millions of neurons working in parallel can process information much faster than any processor known today. Networking simple logical units, and operating them in parallel offers advantages simply unavailable for the fastest single processor architectures. These shared architectures require a huge amount of communication and data sharing which can only be handled by high-speed networks. Fibre Channel not only meets these requirements, but meets them inexpensively. The hardware industry is partly responsible for the I/O bottleneck. By using the processor speed as the primary focus for their sales efforts, the bus speeds have languished. With respect to the new class of processors, current system bus speeds are greatly lagging. This is something like building a mill which can process 1000 pounds of grain a day, and supplying that mill with a single donkey. There is little use for a fast processor that spends most of its time waiting for data to act upon. Whether this data comes from disc drives, peripherals, or even other processors, today's bus speeds would leave most processors idle, and the next generation of processors will be many times faster. Fiber Channel provides the data transfer capability which can keep current and upcoming processors busy. Impact on Mass Storage ---------------------- Today's fastest interfaces are capable of transferring data at around 20 megabytes per second. However, this speed rating is only for transferring data. All protocol intercommunication occurs at much slower speeds, resulting in a lower effective data transfer rates, typically around 11 megabytes per second. This represents about one-tenth of Fibre Channel's current capability. Fibre Channel drives do not suffer from device protocols occurring at slower speeds, since all communication occurs at 100 megabytes per second, including device intercommunication. In addition to this, the drive itself can be placed up to 10 kilometers away from the computer. This would have two effects on the way mass storage is implemented. First, the amount of data a machine could receive would only be limited to the transfer speed of the drive. For high performance disc arrays this could exceed 50 megabytes per second. Machine and disc storage could finally work to provide real-time, full motion video and sound for several machines simultaneously. With Fibre Channel's ability to work across long distances, these machines could conceivably reside many miles apart. For medical applications, computer design centers, and real-time networks such as reservations systems, this capability would be invaluable. Second, such support for transmitting data over large distances would allow disc drives to be placed away from the computer itself. This would allow for centralized data resource areas within a business office, simplifying everything from site planning to maintenance procedures. Indeed a centralized data resource center would be possible for an entire office complex. The development of the Loop will also provide a huge advantage in implementing large capacity disc sub systems. The Fast/Wide SCSI specification has a theoretical upper limit of 16 total devices attached to a single host. The practical maximum is 6 devices. Fibre Channel supports a theoretical limit of 256 devices for a common host, with a practical implementation of 64 devices. This practical limit is a very conservative figure, and implementation with more devices are easily possible. The Loop allows system designers to build high capacity configurations, well into the terabyte range, with much lower overall cost. Finally, Fibre Channel is a serial communications device which has two immediate advantages. First, the cabling necessary to interconnect Fibre Channel devices is very inexpensive when compared to SCSI cabling. Fibre Channel cabling is also much easier to connect, and replace than SCSI cables, which simplifies the entire process of integration and maintenance for a high capacity data storage system. For corporations that are currently grappling with a the complexity of installation, and high-cost of SCSI cables, this feature will prove invaluable for cutting costs and simplifying installation and upkeep. Secondly, implementing Fibre Channel requires less space on the circuit board than SCSI drives. This reduced space requirement would allow the drive designers to include extended features which cannot currently be implemented. For example, a 3.5-inch form-factor drive with Fibre Channel could be designed with dual-port capability, a feature necessary for use with many mainframes and mini-computers. The space saved on the circuit board by using Fibre Channel would allow for the extra connector and additional circuitry needed for dual-port drives. Conclusion ---------- The Fibre Channel will provide the corporations with data in much the same way the freeway system provided motorists mobility. Access to a vast, interconnected information network which is fast, inexpensive, and flexible. With the adoption of Fibre Channel as an open ANSI standard, its effect on the horizon of computing will be nothing short of revolutionary. We have become very good at processing data; Fibre Channel allows us to move it. The ability to share information will provide the impetus for communication, design and development on a scale not previously possible. By facilitating the fabled data-highway, Fibre Channel will accelerate to the Age of Information, as the steam engine moved us into the Age of Industry.