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Grid Computing at a Glance
An anonymous reader writes "Grid computing is the "next big thing," and this article's goal is to provide a "10,000-foot view" of key concepts. This article relates many Grid computing concepts to known quantities for developers, such as object-oriented programming, XML, and Web services. The author offers a reading list of white papers, articles, and books where you can find out more about Grid computing."
And with this change in computing comes another challenge. Not every company has applications that would benefit from distributed computing, but many do. The challenge is making a secure environment that will allow Company A to send their data *and* the software to process that data down the pipe to Company B for processing, meter the usage, and charge back the service. From what I have seen, no farm is really ever utilized 100% of the time, but there are crunch periods where something has to be simulated within a certain timeframe and the existing throughput on hand is not enough. It is those crunch times where you could really use a few trillion spare cycles.
"Beware of he who would deny you access to information, for in his heart, he dreams himself your master."
1. e-mails with "EARN $$$ DOING NOTHING" ...
2. spyware that not only spies but also hijacks your CPU cycles for remote computation
3. dubious companies selling "grid computing" service pop up all over the place
4.
5. Profit?
It may look funny, but what if the next version of Windows comes embedded with this kind of thing? All it would take would be some marketing genius to convince enough people. (disclaimer: yes this is slightly paranoid, it's not intended to be MS bashing, just an example on how this technology could be misused).
The ENIAC Demo Competition
Sun is heavily involved in Grid computing. They provide free multiplatform grid software (including for Linux), case studies, white papers, etc.
They also host an open source project Grid Engine for the software. The software used to be commercial, but Sun bought it and open sourced it, like they did with Open Office.
I have given a lot of thought to this concept in the past and, although I think it has a lot of merit I also think it will require a different underlying software architecture than any of those we use today.
Currently for distributed computing we have Thin-Client/Fat-Server, Client/Server, N-Tier and Shared-Node architectures. I think most people are expecting a Shared-Node or Client/Server for Grid Computing because that is how existing implementations work. The issue with either of those is the size of the work unit. If the work unit is small than the nodes/clients must sychronize often. If the work unit is large then you are more likley to have nodes/clients in a wait state because required processing is not completed.
Using a network style architecture (distributed Shared-Node) raises more issues because of message routing. Interestingly, this is the 'web-service' model! For example a web site must verify a customer, charge her credit card, initiate a shipping action and order from a factory in a single transaction. So you get four sub-transactions. Let's say that each of those initiates two sub-transactions of its own and each of those initiates one sub transaction of its own. We now have a total of twenty transactions in a hierarchy that is three deep. Let's also assume that we only have one dependancy (the verification) before launching all other transactions asychronously.
The problem here is response times, they add up. if the average response time is 500 ms, then three transactions deep gives us 1500 ms. The dependacy, at a minimum, doubles this. So it takes three full seconds to commit the transaction. Something a user might be willing to live with until a netstorm occurs and the response time drops to thirty seconds or more. (Note: Isn't it funny how you never see this math done in the whitepapers pusing web services?) But three seconds is far too long for sychronizing between nodes of a distributed computing grid unless you only have to do it every once in a great while, pushing us towards large work units and idle nodes!
So the Internet itself imposes costs on a distributed model that wouldn't exist on, say, a Beowulf cluster because that cluster would have a dedicated high-speed network. Client/Server architectures work better for the Internet, but require dedicated servers and a lot of bandwidth to and from them.
I believe the real answer lies in what I call a Cell architecture. This would require servers, but their job would be to hook up nodes into computing 'cells' consisting of one to N (where N is less than 256?) nodes. Each node would download a work-unit from the server appropriately sized to the cell, along with net addresses of the other nodes in the cell. Communication would occur between the nodes until the computation is complete and then the result would be sent back to the server. When a node completes its work unit (even if all computation for the cell is not complete) it detaches and contacts the server for another cell assignment.
By reducing cross-talk to direct contact between nodes within the cell we allow smaller work units. By using a server to coordinate nodes into cells we are allowed to treat the cells as larger virtual work units.
Comments?
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Are you an SF Fan? Are you a Tru-Fan?
First off, this stuff has been completely mainstream for over 30 years now. The only thing new is that it keeps getting renamed, This year it's called GRID. I remember when it was called timesharing, and Time magazine had cartoons depicting it is 1973.
The entire GRID standard actually only covers the data transfer and login. Becasue that's the only thing standard about the different types of hardware. You still need to write the software specific to the hardware. Even with tools like MPI programming for Sun big iron is nothing at all like IBM big iron. And you dont exactly use Java. The value is not in the software - that's why it's getting standardized and is given away for free. The value, as always, is in owning a huge pool of computing power and renting it out, or even better, selling it in racks full.
The only people benefiting financially are the people that make the hardware - IBM, HP, Sun, Fujitsu, etc. Just like 30 years ago. Open Source has completely devalued the software - why pay for that, money is better spent on more hardware.
Then there is the cost of transporting the terabytes of data involved in the types of problems you do with these systems. Transport costs are more then the computing costs in many cases - another reason that part got standardized.
Hardware costs are falling FAST. Blade mounted and racked CPU are running about $500/Ghz ($7k for the same from IBM). That means for about 1 million you can get something like 2K CPUs and 2Thz of power, running Linux and all the tools you need. Thats a lot of FLOPS.
For those kinds of costs, outsourcing it at seems silly. You still have to do all software development, data transport, post-processing, and research yourself anyway, and those costs DWARF the hardware/electricity/HVAC costs of owning the hardware and having exclusive access 24/7 until the next updgrade.
- Adam L. Beberg - The Cosm Project - http://www.mithral.com/
Here is a large Grid project that I'm working on.