Location, location, location

OK, so you've worked your way through the first umpty-chapters of this book (and possibly the Sterling, Salmon, Becker and Savarese book, and the HOWTO's, and the FAQ) and have picked a beowulf architecture. You've probably priced it out, as well, as cost-benefit was undoubtedly an important part of your selection criteria. You are probably almost ready to order the parts...

First, however, there are a few things you might not have thought about yet that you definitely need to consider^10.1. Let's arrange them in a bulleted checklist (to see what they all are) and then we'll briefly discuss each one.

• Where are you going to put it? Is there enough space/volume? Is it convenient to the expected users of the system(s)?
• Is the floor of your space strong enough to support the weight of all that iron (no kidding!)?
• How are you going to provide power to all the nodes and switches and so forth^10.2?
• How are you going to remove all that power when is released in the form of heat during operation? Is there enough air conditioning?
• Are there other infrastructure requirements? Do you need to run additional network lines into the space? A phone line? A thermal kill switch?
• Do you need any additional security measures for the space?

``Hmmm,'' you say. ``Spent so long thinking about the programs that I forgot about the physical requirements of all those nodes.'' I thought so. Let's take them in order.

What constitutes a suitable location for a beowulf varies wildly, as one might expect given that beowulf designs vary wildly. You might be getting only eight nodes in mid-size towers, or you might be getting 128 nodes in racks. You could be getting eight nodes in a rack or 128 nodes in mid-size towers. You could be getting eight nodes in a dedicated case^10.3.

God knows, you could even build a beowulf by buying motherboards with CPU and memory, adding NICs, and hand-mounting them in e.g. a common filing cabinet (fitted with a power supply, some cooling fans, and some spacers). With rack (and case) prices being what they are, I've come dangerously close to building a beowulf exactly this way at home and (as PXE/bootp NICs get ever cheaper) I may yet do it. It would actually be kind of fun...

In addition, you might be building the beowulfish cluster just for yourself, and want it in or near your primary workspace. Or you might be building it for a group of users and need it accessible to the group. Or it might even be a ``public'' facility and need to be accessible to several groups. Noise can even be a factor. If you plan to work in the same room as the beowulf, all those fans and disks running at once can produce a very definite rush of white noise in the background. This has never bothered me, but some people are very sensitive to it. All of these things factor into the decision of where to build your beowulf.