Instructables
Picture of iCluster - Build an imac Cluster
What better thing could you do with 4 imacs than turn them into a cluster?

A cluster, for anyone wondering, in general terms, is a group of connected computers that work together to complete a task. 
 
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Step 1: Materials

Picture of Materials
The list is surprisingly short and contains extremely common parts.

4 Apple computers. I used G5 Intel imacs but you can use any Apple computer.
4 Category 5 Ethernet cables
1 10/100Mbps Ethernet switch (minimum 4 ports)
1 key board and mouse
1 USB

In my case, I got all of the imac because they had broken/missing screens. All you need then is a monitor, VGA cable, and VGA adapter depending on the type of port on your Apple.

Step 2: Hardware

Simply plug one end of each Ethernet cable into the Ethernet switch and then the other end into one of the imacs Ethernet port. Repeat for each imac.

Then power everything up.

Step 3: Software

The software is a download from Dauger Research called Pooch. It is available for free at http://daugerresearch.com/pooch/download.shtml for up to 4 computers

Click to download the appropriate version onto one computer. Since my imacs were running OSX 10.5 I used the second download.

Open the folder that you have downloaded called "PoochDemoInstaller". Inside click on the "Pooch Installer" and run it to download Pooch onto your computer.

Next drag and drop the "PoochDemoInstaller" folder onto the USB and copy it onto each of your other three computers and run the "Pooch Installer" on each.

The free version of Pooch only allows you to run 4 computer clusters, but you can buy software from Dauger Research that will incorporate as many computers as you are willing to pay for.

What are "G5 Intel iMacs?" There are G5 iMacs and Intel iMacs, but I have never heard of a G5 Intel. Do you mean that the cluster can be made up of both G5 and Intel iMacs? the two architectures are very different, and I know because I own both a G5 and an Intel.

CVBruce1 year ago
Each of your iMacs should have a 10/100/1000 ethernet port, so using a 10/100 hub is slowing down communication between them. It depends on the workload, but this could impact the speed of the cluster.

I've used Xgrid, and it was pretty cool to see my workload spread over multiple machines, even different architectures, powerpc and intel. I was using software to encode video files.

Another possibility is, if just the screens are bad, then you can still use the GPUs for processing.
Hammock Boy (author)  CVBruce1 year ago
It probably did slow down the speed of the cluster, but I used the 10/100 hub because it was what I had, and since I never had a long term use for it, it did not matter.

I have not used Xgrid before, but I would imagine that it is faster and more versatile than Pooch.
Here is some good info on Xgrid. I don't know that Apple is actively supporting or developing it any more.

http://www.macresearch.org/the_xgrid_tutorials
RogueOne2 years ago
You should check out Xgrid, which is part of the Server version of OS X now. It allows you to "easily" spread processor intensive tasks across multiple Macs.
Hammock Boy (author)  RogueOne2 years ago
Have you worked with it before? It would be neat to get an actual cluster going with 8-10 imacs.
Hammock Boy (author) 2 years ago
If anyone has any ideas on how to improve this I would love to hear them.
Sorry, but doesn't it seem a bit silly to use imacs to get something like this done? wouldn't it be better just to use a few towers, just because all the imacs are self contained and a tad unruly.
Hammock Boy (author)  provocativetimbre2 years ago
I wouldn't mind having a few towers but I only had the iMacs at my disposal. I'm a little confused as to what is wrong with the iMacs bieng self contained since I did have to physically change anything about them. Please explain.
rch2 years ago
Very interesting. I tried to experiment around with a cluster using Linux powered PC's many years ago with something called Beowulf.

Any idea on how long the version of Pooch will run before it expires?

Nice job scoring 4 iMacs, even without monitors, a very nice platform for experimenting with. Where did tou get them, and for how much?
Hammock Boy (author)  rch2 years ago
I believe that Pooch runs for 10 days and then it expires, although, you can immediately download a new copy. I'm not sure then why there even is an expiration date?

The imacs were all free - from a dumpster - my school threw them out because of the bad screens and it was deemed cost effective to just buy new computers. That is also where I got the Ethernet cables. It turned out that the only thing that I had to buy for this project was the network switch. Everything else I already had.

Did you get the Beowulf to work?