What is GRID?
Whereas the Web is a service for sharing information over the
Internet, the Grid is a service for sharing computer power and data
storage capacity over the Internet. The Grid goes well beyond
simple communication between computers, and aims ultimately to
turn the global network of computers into one vast computational
That is the dream. But the reality is that today, the Grid is a "work in
progress", with the underlying technology still in a prototype phase,
and being developed by hundreds of researchers and software
engineers around the world.
The Grid is attracting a lot of interest because its future, even if still
uncertain, is potentially revolutionary.
So the interest comes not only from experts in computer science,
but from scientists, businessmen, journalists and, presumably, you,
the browser of this website!
Imagine a lot of computers, let's say several million. They are
desktop PCs and workstations, mainframes and supercomputers,
but also data vaults and instruments such as meteorological sensors
and visualization devices.
Imagine they are situated all over the world. Obviously, they belong
to many different people (students, doctors, secretaries…) and
institutions (companies, universities, hospitals…).
So far you have imagined nothing new. This is pretty much what the
world looks like today.
Now imagine that you connect all of these computers to the Internet.
Still not much new, most of them are probably connected already.
Now imagine that you have a magic tool which makes all of them act
as a single, huge and powerful computer. Wow! Now that really is
different. This huge, sprawling mess of a computer is what some
dreamers think "The Grid" will be.
What if this dream came true?
Well, if you are a scientist, and you want to run a colleague's molecular
simulation program, you would no longer need to install the program on
your machine. Instead, you could just ask the Grid to run it remotely on your
colleague's computer. Or if your colleague was busy, you could ask the Grid
to copy the program to another computer, or set of computers, that were
sitting idle somewhere on the other side of the planet, and run your program
there. In fact, you wouldn't need to ask the Grid anything. It would find out
for you the best place to run the program, and install it there.
And if you needed to analyze a lot of data from different computers all over
the Globe, you could ask the Grid to do this. Again, the Grid could find out
where the most convenient source of the data is without you specifying
anything, and do the analysis on the data wherever it is.
And if you wanted to do this analysis interactively in collaboration with
several colleagues around the world, the Grid would link your computers up
so it felt like you were all on a local network. This would happen without you
having to worry about lots of special passwords, the Grid could figure out
who should be able to take part in this common activity.
What types of apps can Grid be used for?
A simple answer is that just about anything you
do on a computer you could also do on the Grid.
After all, the Grid is, in some sense just a very
A more sophisticated answer is that the first big-
time users of the Grid will probably be scientists
with challenging applications that are simply too
difficult to do on just one set of computers. After
all, the Grid was originally conceived for these
types of users, and is being built by them, too.
A Brief History
Many of the basic ideas behind the Grid have been around in one form or other
throughout the history of computing. For example, one of the "novel" ideas of the Grid
is sharing computing power. Nowadays, where most people have more than enough
computing power on their own PC, sharing is unnecessary for most purposes. But
back in the sixties and seventies, sharing computer power was essential. At that time,
computing was dominated by huge mainframe computers, which had to be shared by
In 1965 the developers of an operating system called Multics (an ancestor of Unix,
which in turn is an ancestor of Linux - a popular operating system today) presented a
vision of "computing as an utility" - in many ways uncannily like the Grid vision today.
Access to the computing resources was envisioned to be exactly like water, gas and
electricity - something which the client connects to and pays for according to the
amount of use. Ironically, "utility computing" is all the rage again these days, and
used more or less as a synonym for the Grid by some people.
So, yes, there is a certain amount of "reinventing the wheel" going on in developing
the Grid. However, each time the wheel is reinvented, it is reinvented in a much more
powerful form, because computer processors, memories and networks improve at an
exponential rates which are associated with Moore's law.
Because of the huge improvements of the underlying hardware (typically more than a
factor of 100x every decade), it is fair to say that reinvented wheels are qualitatively
different solutions, not just small improvements on their predecessor.
Breaking Moore's law
One of the most misused concepts in the Grid community, and in computing in
general, is "Moore's law". Originally, this was a statement made by Gordon Moore,
one of the founders of Intel, about the number of transistors that could be squeezed
on a silicon chip. In 1965, Moore noted in an article he wrote that this number was
doubling once every year, and over time, this doubling rate has been revised down to
once every 18 months.
Regardless of the fact that Moore's statement was limited to a very specific
quantity - the number of transistors on a chip - it is now used for just about
everything else in computing. "Computing power is doubling every 18 months,
according to Moore's law" is one common misuse of Moore's observation.
Worse, comparisons are made - even in learned journals - between different
quantities that have nothing to do with Moore's law. A frequently heard comparison is
that network performance is doubling every 9 months, and data storage density every
12 months, both "outperforming" Moore's law. The implication is that somehow,
computer processors are not keeping up with data storage and network capacity.
This pseudo-trend is even used by some as an argument in favor of the Grid. The
argument is that you will need to share processing power because your local
processor, which follow Moore's law, will become "underpowered" compared to the
data storage and networking capacity available to you.
Breaking Moore's Law
In fact, this ignores a number of trends which Moore's law does not take into
account. For example, the clock cycle of processors increases along with the
increase in the number of transistors per chip. So processor power, however you
measure it, grows faster than Moore's law. And improvements in chip architecture
and operating systems also make processors more powerful than just the sum of
In short, detailed comparisons of different growth rates with Moore's law are often
misleading. It is best to see Moore's law as simply a metaphor for exponential
growth in the performance of IT hardware - which no one can doubt is true. As a
result of this exponential growth, with every year that passes, the Grid concept
becomes more feasible, because distributed processors can be more tightly
integrated, thanks to improvements in network speeds.
Of course, individual stand-alone computers also become more powerful with every
year that goes by, so the sorts of problems the Grid is particularly useful for will
change with time. Still, there will always be some problems whose complexity, or
dependence on distributed resources, puts them out of reach of a single computer,
but which could be tackled with a Grid. So Moore's law does not threaten the Grid,
it merely shifts the domain of application of the Grid to increasingly complex