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Over the past two weeks I’ve been doing some work with virtualization in the context of Virtual Private Server setups - one physical host machine houses several “nodes” that do the actual processing.There are really two types of setups in this field: shared kernel and and separate kernel.

In a strictly shared kernel setup (like FreeBSD), the root kernel simple creates a new process tree for its nodes, and marks each process with both a process id (pid) AND it’s node id. This is obviously quite efficient, however it lacks the ability to do some of the handy things a separate kernel system provides.

In a separate kernel system (like Xen on linux, or even VMware), much more ram is neccesary since separate copies of all the binaries are loaded into memory. However, that means you can have different kernel version in different setups for testing, as well as better control over “virtual” hardware presented to those node kernels (I am keanly reminded of the networking restrictions FreeBSD jails have, as shared kernel nodes).

Most real operating systems support one setup or the other, however there are a few libraries out there that run on several OSs to allow for both options. Here’s what I’ve found.

Linux - After installing the Xen package, linux supports separate kernel nodes quite well. Despite some of the inherent inefficiencies of such a system, this setup is widely used and provided by companies such as slicehost and linode.

FreeBSD - Out of the box, FreeBSD includes support for Jails. This concept was written in 1995 to basically extend the functionality of a chroot environment. However, there are quite a few shortcomings: each jail is IDENTIFIED by its IP address, rather than a jail id or something of that sort. As such, each jail can have only ONE IPv4 address, and no IPv6. Further, there is no resource control to limit a jail to memory usage, cpu usage, or disk space (see end of paragraph for hacks). Also, a jail cannot do complicated firewalling or tunnels, but that is inherent to a shared kernel system so it can’t be blamed solely on FreeBSD’s implementation. It’s a shame out of the box jails suck so much, since BSD in general is a great system. There are a few patches to provide more jail control, however none are in the current source tree.

Solaris - Supporting 5 different types of virualization, Solaris really takes the cake. Everything works perfectly to any level of configuration. That said, Solaris x86 really is a scary beast. Even if you manage to get it installed, your hardware may still crash it onces a month when it throw a particular hook. If you’re using Sparc hardware however, this is most certainly the way to do things.

In any event, I’m working on getting the patches to FreeBSD installed for jail control, as well as getting some nicer Sparc hardware to use Solaris. With luck, I’ll get good at this virtualization business and perhaps start such a service.

Recently I’ve gotten back into my routing craze… since I can’t get IPv4 space anywhere, I got two 6over4 tunnels and a /48 from Hurricane Electric. My Cisco 7500 is linked up and serves up tunnels to all of my boxes, splitting up the (enormous) address space and doing intelligent routing with BGP in places I have more than one link. It way over engineered, but at least I get to play with such things in case I ever get to work on a large system.

Also, I was bored last night and threw together JustLOLS.com - an aggregator for LOLcats and dogs. Take a look, I’d love your feedback.

I’ll cut right to the chase: I flew!

This picture doesn’t show it well due to the long grass, but I am in fact flying. (I stalled right after this picture was taken, but that’s beside the point!) This isn’t even with good wind - when the wind was favorable, I flew near half way down the hill. Despite the police, high-tension power lines inducing current in the glider frame, and fussy wind, I left the ground. Check out the glider section for video, more pics, etc.

Today I did a lot of math regarding the lift of a non-airfoil wing. From the math and review of the videos, my best bet is that we aren’t properly maintaining the right angle of attack during takeoff. The leading edges aren’t near strong enough either, but that’s something I can’t fix (if anyone knows where to get thin wall aluminium tubes I would love to purchase two…) In any case, I will be in NJ at the end of this week. I have a couple ideas as to increasing the angle of attack. I’ll be sure to post pics, and with any luck video of some flight!

This post is divided into two parts: Things I’ve done recently, and things I’ve acquired recently.

Events

Last Sunday I was up at 6am to do communications for the MS walk in Worcester. I didn’t actually need to do anything.

This Sunday I was up at 5am to get to the MIT Swapfest. Usually Ken and I come back with both more money and more devices. However, this trip was in the interest of emptying the apartment for the summer. As such, I bought nothing, came back with $310 more, and got rid of about 30 cubic feet of computers and routing equipment. I spent most of the money on a new radio, but that’s beside the point…

Monday (yesterday) I was up at 4am to do radio for the Boston Marathon. I was an operator for the medical teams. It wasn’t really the most exciting thing I’ve ever done, but it certainly got me out of the house. It was the biggest event I’ve ever done, but it was also the most organized so it wasn’t that bad.

Tuesdsay (today) I had an interview at Applied Communications in Northborough. They aren’t quite the same as many of the other companies to which I applied or from which I got offers, but it sounds like they have the opportunity for me to travel a good bit and work on some very different projects. They seem to like me a lot. If they can come through with an offer close to some of the others, I’d likely nab the job.

Additions

I’ve got a few small things recently, but the two large additions to the RF section of the apartment are as follows:

An HP 8924C service monitor. This handy device has an RF generator and analyzer, as well as a spectrum and network analyzer. In addition to the analog functions, it does all sorts of encoding models such as CDMA, GSM, EDACS, etc. The reason I could get it for $hundreds not $thousands is it’s title: Cellular Monitor. It was produced for cell phone techs to trouble shoot phones (back when this was done rather than just throwing them away). As such, hardly anyone on eBay found it, and I nabbed a sweet device. Here’s a pic of the analyzer sweeping a duplexer:

A Yaesu FT-8100R mobile radio. This is a dual band (2m/70cm) ham radio that has two features I needed: cross band repeating and wide band receive to 1.3ghz. In general I stay away from ham equipment (versus commercial) since it tends to be much lower quality (ham equipment doesn’t need to pass FCC specs - it’s up to the operator). This is in fact the case with this radio: the deviation is a little high (gets to 6khz), it’s moderatly deaf (opens at -120dBm as opposed to my Motorola’s -158 dBm) and the output frequency is a bit off (1.3khz on VHF and 700hz on UHF, compared to 200hz on my motorola). Regardless, it does several functions on different bands plus wide band receive, which isn’t something commercial equipment is made for. It has a different purpose, and if I need higher performance for a task I’ll just use a Motorola.

I got my pretty new radio a few days ago. My Motorola XTS 2500 is quite nice, I have to say. It’s the second to most epic handheld Motorola makes. In addition to the things my HT1250 does like MDC signalling and whatnot, the XTS series supports APCO Project 25. This standard, P25 for short, is a digital protocol for signalling and voice over radio. It’s mostly used in the public safety bands, since digital works better than analog covereage (in general: if the packets can be pulled out of the noise at all, the original audio is maintainted). Kurt, N1PFC came by and helped me program the radio for all my various Ham things in the area (I didn’t own a VHF handheld before so this list is pretty extensive) as well as his P25 Ham repeater not far away. Yay

In other news, I finally got around to doing my Extra class ham license. I got a new call sign while I was at it, and as such I am now NA1C.

In an effort to promote radio and space to other WPI students and staff, Theo, KC2RMJ and I (KB1OZL) put together an event with WPI Wireless to talk to the International Space Station during a particularly good pass last November. I found the pictures of the event and thought they were nice.

I put together one of our (WPIWA’s) smaller towers for the event, and kept it outside my apartment for a few days leading up to the event. Also, I built a 2 meter J Pole antenna since it had pretty good gain at the horizon to help lengthen our window. I modified it a bit from what hams generally use (I used much larger tubing), but as I expected it made the antenna much more wideband. We got about 6 dBi, at <1.5 SWR across the band. Nice!

Continue reading ‘WPI Wireless talks to ISS’

I heard back in the day of someone building a hang glider from a tarp and bamboo… While I went slightly less ghetto, this Winter break I built a hang glider with the help of several friends. The thing is quite… well… take a look at the project here.

A while ago I posted regarding the network when I moved into my apartment. This winter break we finally got around to working on things and taking it from a cluster of gross to a pretty little network of lights. Internally, we have 3 separate IP segments, bridged by our Cisco 2500 routers. Additionally, we now have VPN tunnels to a few friend’s apartments as well. Since the Department of Defence network is not routable publically anyway, we chose to implement our main backbone on the 11.0.0.0/8 network, with other segments on 172.20.10.0/24, 10.0.0.0/8 and 192.168.0.0/16. I suppose it isn’t strictly neccesary, but at least it was worth implementing since we learned a lot about routing in the process. I can actually configure Cisco devices properly now!

Being an ECE student has it’s perks… The head of the department, Prof. Looft, sponsors a newbie gliding event every year with the gliding club he belongs to. There were about 25 random WPI kids out there, and we all flew. Very epic!

Continue reading ‘I Very Much Like Flying’

This August I moved into a school-owned apartment while I work for the Manufacturing Eng department designing and building prototypes for outside companies. It’s handy because I’ll be living there next year so I won’t move twice. I appear to have accrued a large amount of computing and routing equipment over the last year… Take a look at the racks:

Continue reading ‘My New Apartment’

Over the past few days I’ve been working on a z80 computer. It’s on breadboards, and includes 2M flash, 32k static ram, and 3 IO ports. It’s quite interesting, and is clearing up lots of my low-level computing knowledge. More on that in a few days.

Today I put much larger motors on the X and Y axis of the mill, having already put a larger motor on the Z axis. The new motors looked great and ran equally as great for about 3 minutes… The new motors pulled much more current than the previous, and I couldn’t remember the ratings on the NPN transistors I used. Turns out its less than what i need.

When I get around to it I’ll make a new driver board with Mosfets rated at 50 amps, should take care of it. The supply I’m using is 5v at 50 amps, so I don’t think any single line can exceed its rating.

The new mill is very slowly coming along… I can’t wait until I can make huge things though.

Tonight I finally got around to putting on a new Z-axis motor. It’s about 5x the torque of the previous, plus 4 times as many steps per revolution (so 4 times as accurate). Since there is more torque, the rapid in the Z-axis is now 11 ipm, up from about 1.5 ipm with the previous motor. Yay!

I’ve been using the mill succesfully for a few weeks now making several PCBs. It’s really been great being able to design a board and have it in my hand within an hour. Unfortunatly, the Z-axis motor appears to have bit the dust. I came back from the other side of the shop to some bad-sounding noises, and the bit was quite embedded in the pcb… so no boards until I can take a look at that.

I made several boards for my friends MQP (a kind of senior thesis project at WPI). His team is making a large rocket with an onboard computer and needed a wireless control. I designed and built him a transmitter and receiver from Lynx chips. They seem to work amazingly… more on that after the launch.

My and Ryan just after testing the range. We look oh-so-happy:

Very slow progress continues on the new 44″x22″ mill, but what little time I’m not doing school work I’m doing the rocket project. Hopefully things will clear up a bit soon.

I’ve been working on my CNC mill over the past month. It’s based on a small manual mill made by Proxxon. I have 3 nice unipolar stepper motors, one on each axis. The motors are controlled by 3 L297s from ST Micro (these are REALLY amazing by the way…) to 12 TIP102 transistors used as ground side switches. This board is then hooked to the parallel port of my laptop, running EMC2 on a real-time kernel. What does all this mean? I can now take a CAD/CAM model and have a part of it, all with tools in my room. Now THAT is cool.

Also, I finally got pics and video of the new capacitor bank up. Be sure to check out the CNC Mill and the Capacitor Array!