Desktop Cluster

[Master of Reality]

I've got three or four PCs lying around that have about 500Mhz processors (with one 1.5 GHz) and I was thinking; they're just sitting there, and my desktop is rather slow at... most things. So why not cluster them together. My first obstacle is: is it possible and beneficial in any way to do this?

[Void Main]

Well, I don't think there is an "easy" way to do what you want. There is nothing I am aware of that will simply turn your 4 single processor 500Mhz machines into a virtual 4 processor 500Mhz machine or a virtual 1 processor 2Ghz machine to run your normal apps if that is what you were after. If there is something like that I would be interested as well. The only thing I have used that would come close to that is PVM:

http://www.csm.ornl.gov/pvm/

This requires specially built apps though and is more along the lines of a Super Computer architecture.

[Calum]

aha! the perfect opportunity for me to ask: what benefits does clustering have then, and what environments would it normally be used in?

[Master of Reality]

studying genomes and other computational biology is one of the more frequent uses ive seen clustering used for.

[Void Main]

And there are more than one type of clustering. The kind I mentioned (PVM) is used when you need a lot of computational power such as in supercomputing. However, you can just run any old program on a supercomputer cluster. It's a little like running a single threaded application (like Firefox or OpenOffice.org for instance) on a multiprocessor machine. It's only going to use one processor on that machine. On supercomputers the applications have to be specially written so large tasks can be broken down into many smaller tasks and distributed evenly between all processors. A cluster with 1,000 processors can basically perform a large task 1,000 times faster than a single processor machine. But again, the app has to be written to take advantage of the technology.

The other type of cluster is very common in businesses. We actually run many computer clusters where I work. For instance, we have web server clusters, mail clusters, proxy clusters, database clusters, etc. These kinds of clusters are designed to distribute the load evenly from clients and provide high availability. That is, one machine can fail and the others will pick up the load.

The wikipedia has a nice writeup as usual:
http://en.wikipedia.org/wiki/Computer_cluster

Here you can find the top 500 supercomputers:
http://www.top500.org/
Of which Linux is by far the OS of choice:
http://www.top500.org/stats/27/osfam/

I also should have also mentioned Beowulf previously:
http://www.beowulf.org/

Nice cooling system on this Linux cluster:

[JoeDude]

LOL...I had to cool like that in Korea...it's not really that funny

[Calum]

that's a brilliant picture! i wonder if they all have CD drives? you could use them (or it) to burn a whack of CDs all at once, though you would have to have a few technicians running around to take full advantage of it.

i like the sound of that redundancy, that would give a business real peace of mind. it's like RAID, except with processors, yes?

[Void Main]

Yeah, it's a little like RAID for resources other than disk. It's like RAIS, or maybe RAS (redundant array of services rather than redundant array of inexpensive disks). Now that's for the business type of clustering I was referring to. The supercomputer type of clustering would be more along the lines of RAP (redundant array of processors).