C.O.D.

I'm slowly sliding into the last few weeks at my current institution, and am very much looking forward to the summer, and the resumption of several other projects which I have simply not had the time to properly attend to as of late. I pointed out in my last post that my senior thesis in Economics was finally complete, and I'm also pleased to announce that my research and writeup efforts earned me co-authorship on a paper which will be presented at a conference in London in several months. Assuming the article makes it to some online-accessible medium, I'll post a link to it here.

I haven't really spent any blog time explaining what exactly my thesis is focused on, so I'll provide a brief introduction now. Economics models can be very very difficult to validate. One interesting way to experiment with a model however, is to build a computer simulation of it. However, as soon as you attempt to do so, especially from a comp-sci/programming perspective, you realize just how 'top-down' a lot of the logic inherent in these models really can be. For my thesis research, we started out with a canonical Neo-Kaleckian growth model (a form of demand-led post-Keynesian system) and constructed a computational agent based simulation of it. The results actually proved to be very interesting, and with any luck, our modifications as well as some of our results and conclusions should open up a new line of investigation surrounding this particular model. As this is a technology blog, I wont get into the actual details of the economics. However, I will add that we used the Repast toolkit to implement it. Repast was a fun ride, but in the end it suffered the same frustrating traits that all frameworks ultimately fall victim to; they speed things up right up to the point where you need to do something the framework wasn't designed to allow, at which point they slow you down a lot. In the end, I cannot blame the toolkit for this, as all good software always comes down to good engineering, which always inevitably reverts to good planning, leading to the issue of knowing at the start exactly what it is that you want to do with something. Frameworks can be misleading (in letting you think that you should just follow some simple rules, and extending things later will always be easy) but they are never a substitute for careful specifications. Of course, when creating a research tool, you end up with the unpleasant situation of the software changing its own requirements.

I've also just received word today that another paper I helped to write this semester on methods of software engineering education (as applied to a method we tried here at Trinity) was accepted at a conference focusing on... software engineering education. Last semester I TA'd a course in software engineering which included a practical component focusing on a system that I designed last year with the help of another CS major to log how computer-science students spent their time (in terms of a breakdown between the various critical steps of a process). This simple web application proved to not only be a useful tool for logging time, but also for teaching teams how to carefully plan and extend an existing system without perfect documentation on a timetable while assigned to teams defined by their characteristic asymmetric skill sets. It was a lot of fun to structure, and we ended up getting enough novel and interesting things out of the experience to take a stab at a paper, which then turned out pretty well.

But, as I said, the year is winding down and I am looking more and more to my next two years as an MBA grad student at MIT Sloan, with just a few things standing between me and that inevitable and very thrilling future. Of course, the biggest (in terms of sheer weight) is the new Trinity cluster. As I said in my last post, we received much of the last of the hardware that we need to make everything run. As it stands now, we actually have all the critical hardware components, and are in the process of settling some software issues.

As I said earlier, we received our new ethernet switch as well as its associated fiber optic patch cables (LC/LC duplex multimode) necessary to connect the bladeframes to the network, as well as the FibreChannel switch to the SAN and the bladeframes. The switch is a cisco catalyst 3750 with 6 1000SX-BASE SFPs and 1 gigabit copper SFP. The gaggle of day-glo orange is of course, the fiber. I wish it looked 'neater' but considering that it's six feet off the ground, I'm not too worried about something snagging it. As you can see in this picture, we also have our qLogic SANBox 1400 (FibreChannel switch) located in just about the same place in the rack. An old netgear 10/100 rackmount 12 port hub is serving as a makeshift shelf of sorts. The other box sitting on top of it is a 16 port 10/100 switch that is giving us a few more ethernet ports. We're actually going to be receiving another ethernet switch (copper only this time) to replace this netgear switch as well as the little 16 port sitting on top of it. The new switch will plug into the 3750 and allow us to save a port of our drop and presumably a port on the big switch that serves the MCEC.

To keep everything safe and cozy, we're using RFC1918 subnets for both management and the blades themselves. These networks will only be accessible from specific other hosts and networks on campus alleviating a lot of the security pressure on our end. Both networks will actually be on the same vlan (for various reasons) but each will be on a different logical layer 3 network. These networks are actually both already configured, but as one of them is not plugged into the larger network (namely, the management network which is running over the netgear and it's little trendnet friend) I prefer to consider it the future.

As I mentioned earlier, our AC unit has finally been repaired as well. Apparently the issue was some kind of component failure in one of the two compressors. It's been fixed, and is now pushing cold air into the floor (it's set to 68) however, I am still very nervous about the return air supply. Also, it keeps complaining about 'low humidity' (which makes sense, as computers like a relative humidity level between 40% and 60% to keep static from building up) but I actually see this as a symptom of poor air flow. A lot of the air put out by this unit is going into 61A but at times (if the door to 61A is closed) has serious trouble returning to the liebert unit. A lot of air is getting sucked in through the cracks around the door to the hallway meaning that if you leave the door to 61A closed, the 'low humidity' alarm will go off as the air the unit is getting back is coming around the long way, and is already very dry (or, rather, not humidified). These units were designed to cool one really big room redundantly. Now, the unit that we're using is kind of awkwardly boxed up in a rather small room, and is being asked to cool a bunch of computer equipment in the room next to it. This is less than ideal, but this is also a very big air conditioner. I'm confident that it will be able to fill our needs nicely.

Ultimately though, the system is up and running, the SAN is working, the ethernet blinks, and the pressures is now on getting the software configured. There are a couple of wrinkles involved in this step, which I hope to get into in a future (hopefully the near future) post. Stay tuned!

Back in action

It's been quite a while since my last post, mostly on account of my senior thesis in economics, which is finally complete and turned in. In the mean time, a lot has happened on several fronts. A messed up data stream at WRTC has pretty much killed the 'online' aspect of The QuadCast (short of plugging a radio in to a computer, there is no easy way to capture the stream, at least, not one as effortless as a cron job and a streamripper). The cluster is progressing quite well, at least in terms of hardware. We finally have had our air conditioner repaired (evidently a component of one of the two compressors had failed) and it's producing cold air (but I am still nervous about how well the hot air will return to it from 61A). We have received our new cisco fiber ethernet switch, and both the fibre channel and ethernet multimode patch cables have all been installed. We have had our network appropriately subnetted and configured logically (more about that later) and the system is actually turned on and running. All in all, we're way behind schedule but looking pretty good going forward. With any luck, it will actually turn out something during my tenure! Oh, as one other last aside, we managed to find a buyer for our older Alphacluster which is kind of cool. It's not often that you get to earn a profit for your department.

I'll fill in all of the gaps of this soon, along with new pictures and details as soon as I find the time to really buckle down. I'll tackle it in a few posts over the course of the next few days.