Ask Slashdot: Building a Cheap Computing Cluster?

New submitter jackdotwa writes "Machines in our computer lab are periodically retired, and we have decided to recycle them and put them to work on combinatorial problems. I've spent some time trawling the web (this Beowulf cluster link proved very instructive) but have a few reservations regarding the basic design and air-flow. Our goal is to do this cheaply but also to do it in a space-conserving fashion. We have 14 E8000 Core2 Duo machines that we wish to remove from their cases and place side-by-side, along with their power supply units, on rackmount trays within a 42U (19", 1000mm deep) cabinet." Read on for more details on the project, including some helpful pictures and specific questions. jackdotwa continues: "Removing them means we can fit two machines into 4U (as opposed to 5U). The cabinet has extractor fans at the top and the PSUs and motherboard fans (which pull air off the CPU and remove it laterally — (see images) face in the same direction. Would it be best to orient the shelves (and thus the fans) in the same direction throughout the cabinet, or to alternate the fan orientations on a shelf-by-shelf basis? Would there be electrical interference with the motherboards and CPUs exposed in this manner? We have a 2 ton (24000 BTU) air-conditioner which will be able to maintain a cool room temperature (the lab is quite small), judging by the guide in the first link. However, I've been asked to place UPSs in the bottom of the cabinet (they will likely be non-rackmount UPSs as they are considerably cheaper). Would this be, in anyone's experience, a realistic request (I'm concerned about the additional heating in the cabinet itself)? The nodes in the cabinet will be diskless and connected via a rack-mountable gigabit ethernet switch to a master server. We are looking to purchase rack-mountable power distribution units to clean up the wiring a little. If anyone has any experience in this regard, suggestions would be most appreciated."

Comments

don't rule out

[v1]

throwing gear away or giving it away. Just because you have it doesn't mean to have to, or should use it. If energy and space efficiency are important, you need to carefully consider what you are reusing. Sure, what you have now may have already fallen off the depreciation books, but if it's going to draw twice the power and take double the space that newer used kit would, it may not be the best option, even when the other options involve purchasing new or newer-used gear.

Not saying you need to do this, just recommending you keep an open mind and don't be afraid to do what needs to be done if you find it necessary.

Re:don't rule out

[Farmer Pete]

But you're missing the biggest reason to do this...The older hardware is already purchased. New hardware would be an additional expense that requires an approval/budgeting process. Electricity costs lots of money, but depending on the company, that probably isn't directly billed to the responsible department. Again, it's hard to go to your management and say that you want them to spend X thousand dollars so that they will save X thousand dollars that they don't think they need to spend in the first place.

Re:Don't do it

[Anonymous Coward]

Seriously, it isn't worth your effort - especially if you want something reliable. People who set out to make homemade clusters find out the hard way about design issues that reduce the life expectancy of their cluster. There are professionals who can build you a proper cluster for not a lot of money if you really want your own, or even better you can rent time on someone else's cluster.

If the goal of this is reliable performance, you're absolutely right. But if the goal is to teach yourself about distributed computing, networking, diskless booting, all the issues that come up in building a cluster, on the cheap - then this is a great idea. Just don't expect much from the end product - you'll get more performance a modern box with 10s of cores on a single MB.