Back when I was a teen ager, and into my twenties, The
Cray was the finest, fastest, most powerful, and most exotic computer in
the world. These machines cost millions of dollars, and were, virtually,
custom built, and installed. Adding to their mystique, were the uses to which
they were put. There were Cray computers at the super secret NSA, advanced
labs like Sandia, and Los Alamos, and places like the National Center for
Atmospheric Research, NASA, and Caltech/JPL. The computers themselves were
somewhat of a secret, and were little known, or known only by reputation.
These computers were so secret, that upon their retirement, they generally
had to be dismantled, and destroyed. These super secret, super powerful computers
were not made in Silicon Valley, or even in Los Angeles, or New York. They
were made in Chipewa Falls, Wisconsin. This added to the romance of these
limited production machines. I.B.M. DEC, Data General, and other companies,
would make large numbers of computers like the Ford or GM of the computer
industry. In contrast, the small number of craftsmen at Cray would only make
a limited run of high quality, specialized machines in their little shop
in northern Wisconsin, in the manner of Rolls Royce. Unfortunately, it is
rather difficult to get exact specs on the Crays, other than their performance
in gigaflops. This is in part due to the custom nature of the machines, but
is reminiscent of the Rolls Royce policy of not disclosing engine horsepower
ratings for their cars.
The Cray Operating System (COS), and latter Unicos, are
both variants of Unix. The native programing environment is C, though there
is also FORTRAN available. Cray went out of business for a while (1995), but
was eventually resurrected, and is now associated with Silicon Graphics. There
is little hope for the non-millionare to produce a computer which will rival
the contemporary Cray, but it is possible to set up a machine which can mimic
the old Cray-1, Cray-XMP/YMP, and possibly the Cray-2 or Cray-3 machines.
I have gleaned some information on the specs of the machines, and have entered
it in the table below. The problem with setting up a table like this for
a custom machine, is that the specs do not cover the whole series produced.
In particular, it is difficult to get exact data on the mass storage systems
used. Often, these storage systems were not even built by Cray, but were
ordered from other sources by the purchaser. Cray machines use a variant
of Unix, and will often use resources located on other machines. This is
particularly true of hard drives, and other mass storage systems. In many
cases, other computer systems would function as file servers. The Cray would
load needed data into it's silicon disk (ssdisk), as needed, and use this
as a virtual hard drive. The table is primarily based on information from
NCAR, which has been using Crays from the earliest models, and continues
to use them today.
As can be seen from the table, incomplete though it may
be, it is well within the capabilities (and budget) of the average enthusiast
to put together a machine to roughly equal some of the earlier Crays. The
main problem is with the CPU. Cray rates their processor speed in nanoseconds,
rather than the more familiar Megahertz. It is easy enough to convert, and
I have done so in the table, giving both numbers. It can be seen that current
processors from AMD, and Intel easily match, and exceed the speeds of the
early Crays, but there is more to processing power than clock speed. Crays
used 64 bit processors, while the Intel/AMD units use 32 bit processors with
64 bit data paths. Some Cray processors have two math units. There are other
architectural differences as well. Cray machiens were also the earliest to
use what we now call RISC processing. There can thus be no direct comparison,
at least not on the basis of speed alone. There is also the fact that, except
for the Cray 1, Crays used more than one CPU. There are, in addition, some
features that have never been implemented on standard PC's. One of these is
the solid state disk, which can greatly speed up data intensive calculations.
My initial Cray wanabee was a poor excuse for a Cray,
and I would put it at a level between the Cray-1, and the XMP, without the
speed offered by the solid state disk. Varmint Al, who used to work at the
Lawrence Livermore Labs, and used Cray
computers, puts his Pentium
200 (64mb/2.7gb) machine at about a fifth of a Cray-1. I will take his
word for it, as he claims to be able to run the same modeling software on
it that he ran on the old Cray, years ago. It is a credit to the architecture
of these machines that a Cray using an 80mhz cpu, and 4mb of ram can be considered
5 times the machine as one using a 200mhz cpu, with 64mb of ram.
My machine is presently configured, as shown above. It
runs the Sun version of Unix, and I have linked resources with my Solaris
machine, in the manner that was common in multi computing environments of
a decade or two ago. I would stack my Cray emulator up against a Cray-3.
Like the Cray-3, my Sun e450 has quad 64 bit RISC processors, running at
a speed of 480mhz. It has 4 gb of RAM, which is more than the machine I used
to set up my table had, but which was not unusual in other examples of the
Cray-3. I also took some liberties with the amount of hard drive space. My
Sun machine has a pair of 16gb SCSI drives, installed by Sun. These hold
the OS, and some other files, as well as most of the working directories.
This is already more than was common, even on supercomputers, ten years ago.
In addition, I added a raid controller, which controls 8 hard drives of 300gb
each. Using RAID 5, this gives a capacity of 2.1 TB, with redundancy. Amazing!!
I am getting to be a big believer in RAID, particularly
modes 10, and 5. Mode 10 gives great speed, as well as redundancy, while
mode 5 gives great capacity, and redundancy. Take your pick.
This table is based on actual machines used by NCAR over the years. The
Cray 2, and 3 could have as much as 4gb of ram. The Cray 3 could have as
many as 16 processors, while the 2 can have as many as 8. Mass storage was
added according to the needs of the customer. many of the Crays of this era
were capable of 3 or 4 megaflops.