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					        GRID

NCSET   Farhad
        Javidi
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
  resource.
 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!
The Dream
 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
  big computer.
 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
  whole organizations.
 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
  their transistors.
 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
  problems.
Questions?

				
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posted:8/18/2012
language:English
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