Hard Drive: SEAGATE: ST136475FC 36400MB 3.5"/HH FC-AL FIBR

S T 1 3 6 4 7 5 F C    SEAGATE
                                                      Native|  Translation
                                                      ------+-----+-----+-----
Form                 3.5"/HH               Cylinders        |     |     |
Capacity form/unform 36400/      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                                  

General

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.