New Data Integrity Tools

I’ve recently added a couple tools to my standard set, and have at least a 4x improvement in the safety of my data by doing so.

The process was complicated a bit because I’ve become very sensitive about only depending on FOSS tools (ex:As much as I like SublimeText2, I stopped using it because it once demanded to be updated before it would run.), but frankly I think that constraint produced better results than I would have reached without it. Because it was something of a hunt, I’d like to recommend the particular tools I settled on, in particular are KeepassX, Attic, and Seafile, described individually below.
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Quick Laptop Sleeve

HalfIn
I noticed I was scuffing up the not-my-laptop that I’ve been carrying, so I did a little “30 minute” sewing project (that actually took over an hour because I’m apparently retarded) after I burnt out on other things for the evening.

The intention is a little sleeve that will be snug enough to retain the laptop, and let me slide it between [note]books, etc. in a bag. That means a little long, with thick hems on the open end for retention, and no flaps, fasteners, or protrusions to hang up on other things in the bag.
Basically, I measured the wrapped length and width of the machine (to accommodate for thickness), cut a piece of fabric I had around to the full wrapped long dimension (+1.75″ for hems and clearance) and half the wrapped short dimension (+1″ for seams), hemmed the short ends, folded it in half, ran a seam down the sides, half-assed wrapped the first 2″ of each side seam, and called it adequate.


Upside:
  • I can still sew well enough to go from conception to part on something trivial almost instantly.

  • My neglected sewing gear is still in working order.
  • My vintage sewing machine got her recommended periodic exercise and lube.
  • The finished product is functional and looks fine.

Downside:

  • I initally cut the circumference of the machine … in both directions. 1.9 sleeves worth of fabric!

  • One day, I will sit down in front of a sewing machine and thread it the right direction the first time. That day was not today. Bobbin thread/direction? -Easy. Complicated path through the tension and take-up? -Easy. Passing the right way through the needle? -Derp. I’ll claim it’s the Singer vs. White thing if challenged.
  • I had to look it up and still managed to use the adjustable hemmer wrong in two different ways, one hem failed to fell, the other is not really straight.
  • I added allowance for generous 1/2″ seams intending to cut after … then sewed 1/4s and had to redo the side seams to make it snug enough.

Using my venerable old machine always makes me feel like it and 3 generations of my family are judging me when I do something inept or half-assed on it, which probably makes my projects better.

I think I’m satisfied. I’d like it to be just a hair snugger, but the fit is pretty good and snugger would have run the risk of finishing then not being able to get the machine in. I think I want to make some kind of companion pouch for the power brick, but I’m not sure how, an attached pocket would ruin the slip-between-things-in-my-bag functionality.

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Inspiron 11-3000 Notes

Inspiron113000

The KAOS lab recently bought a fleet of five Inspiron 11 3000 3138[PDF Warning] (Celeron N2815/4GB/500GB)laptops. They’re tiny little machines with 8 hour claimed battery lives, they’re pretty cute and sort of obstinate.

I borrowed one to play with, notes:
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Prezi

My Instructional Technology class asked us to play with Prezi, Some thoughts:

  1. I don’t think I’ve ever seen a presentation using Prezi that wasn’t made worse by it. Sometimes because the internet connection wasn’t good enough to support it, and it wasn’t installed locally. Usually because the transitions were distracting. Sometimes because there were better less spatial schema available for the information.
  2. I don’t think this is necessarily a general problem with Prezi, I think it is just that we have decades of experience designing slides, and (at least in principle) roughly know how not to suck at it, while no such body of knowledge exists for zooming presentations. Especially because it plays on our tendency to use novel features because they are there, just like we’ve slowly learned to exercise restraint with the awful things that can be done with fonts and colors in most slideware.
  3. Prezi’s designers clearly read Jef Raskin’s The Humane Interface and took it as gospel. It looks like a subset of a ZUI (Zooming User Interface) that he advocated for, unselfconsciously ignoring subsequent criticisms.
  4. Building something like that on top of Flash in this day and age is utter, inexcusable insanity. I went through four OS+Browser combinations before I found an environment where it didn’t crash Flash immediately.
  5. Their motion interpolation is the most annoying, nauseating motion in a world of annoying, nauseating smooth scrolling schemes.
  6. Sign up with your .edu address through the “for education” link if you have one. You basically get the small paid plan for free.
  7. By default, they appear to send you email every fucking day, and have one of those intentionally obtuse tools (not accessible except for via the unsubscribe link in the email footer, unsubscribe button set up to look like it might delete your whole account, etc.) to fix it.

Bah. 99 times out of 100, I’m sticking with Beamer.

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WNR3500L Repair

Some years ago the KAOS lab bought a number of Netgear WNR3500L routers to use as network glue. A pair of them have been in constant service since 2011 in the lab and machine room, and both of those died in the last two weeks. I’ve finally satisfactorily tracked down the culprit, and figure it’s worth a quick write up.

The WNR3500L is a bit of a false-promise machine; it was sold as an “open router” with excellent community firmware support, but it has some pretty extensive blobs that mean it really only runs versions of DD or Tomato with a small range of 2.6 kernels.

I initially just swapped the first one to die out for a spare (which happened to be flashed with Tomato instead of DD, it was an experiment when they were first set up), and reloaded most of the settings by hand (we failed to save or document many of the settings elsewhere. Our fault.) until I had time to investigate. When the second one died, it became urgent.

WNR3500LScrew

Conveniently, the WNR3500L has a 3.3V RS-232-like serial port (115200/8/n/1) under an easily removed panel, retained by one small torx screw/pin thing (Both are out in the picture while I was figuring out which side was which).

WNR3500LBP

This leads to another victory for the Bus Pirate. Any 3.3V compatible UART adapter would work, but the bus pirate has much nicer cables for this sort of thing. In retrospect, those headers are correctly sized to just plug the female harness ends directly, but I used clips out of habit.

It turns out they were booting right up with only warnings, but the configuration was sufficiently garbled that neither the WLAN nor the Ethernet ports were coming up. I blew the first one’s settings away (note: at least on the old version these were running, reboot TWICE after clearing the NVRAM to get back to a consistent state: the first time it writes default values, the second time it boots cleanly). With the software-only nature of the problem established, I took more time to investigate the second one, at which point…

nvram show
[1310 lines excluded]
size: 32782 bytes (-14 left)

Well, There’s Your Problem.

Turns out the tiny little log fields for monthly traffic statistics filled up the nvram and were causing configuration corruption, and thus failures.

There are some forum threads and bug reports on the matter, and it was fixed about two years ago with a test to prevent writing past the end of the file, a default setting to automatically delete traff logs after 12 months, and various other enhancements. Now that we’re up and running again it isn’t desperate, but it looks like there is a DD release from mid-2013 with the fixes applied that still supports these things, and they are probably due to be re-flashed to keep this from happening again.

Lessons:

  • My home OpenWRT on a TP-Link 1043ND uses a connected USB key for logging and such. This is a much better behavior (like most things in OpenWRT: DD-WRT appears to be kind of an unmaintainble mess).
  • Keep an eye on appliances like routers, they’re still just computers.
  • Back up your damn configurations, or at least retain copies of the information required to regenerate them. Regenerating settings, especially when it involves manual tasks like MAC address hunting, sucks.

Other notes:

  • These things’ bootloaders appear to always look at 192.168.1.2 through the non-WAN ports for a tftp payload named vmlinuz. There may be a way to disable that, but I think I’d prefer to leave it on, since it only enables local attacks and provides a rescue mechanism.
  • The WNR3500L has a documented weakness about WAN-LAN throughput with various firmwares. Our uplink is actually good enough for it to matter, so perhaps one of the newer versions will improve that.
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Debian init Decision

The Debian ctte init discussion, which has been the drama that keeps on giving, appears to have finally had a decisive vote for systemd [EDIT: I was over-ambitious about decisive. The drama continues.] as the jessie init. Some notes:

  1. I found out that the FLOS neologism that is my fault is being used in the discussion. I’m not sure that I’m entirely happy about that, but I do think that we should be self-aware about building something very different from the Unix tradition.
  2. Even with my well-documented distaste for some of the philosophy (and rider components) in systemd, my experience and taste is that Upstart is the worst possible choice, and nothing else seems to have a chance. Letting the Canonical folks continue to act like Upstart isn’t universally technologically and philosophically unsatisfying to is wasting everyone’s time.
  3. The FDO agenda has largely succeeded, a bunch of the upper layers of the ecosystem are developing dependencies on systemd-coupled interfaces. This is largely because the previous interfaces being used for much of that functionality were the same developers’ now-abandoned earlier projects, which turned out to be disasters. This would be fine if there were even signs of competing implementations of those interfaces, or if the design of those interfaces weren’t such that it would be almost meaningless to attempt one, because the parts were designed as part of an integrated stack. I don’t see, for example, a clean standalone logind implementation (since it assumes things that only sysmted does further down the stack) or a nice healthy syslog-ng/rsyslog arrangement for journald. The FDO folks made an end-run around any kind of discussion of the merits of their plans by implementing quickly, getting a few of them widely adopted (initially by sheer political blustering), then coupling the rest of their design to the parts others were on board with. I’m pretty sure they consider that some kind of virtue.
  4. Related to (3) the integrated service manager over rcconf system discussion seems to have been decided on Linux up and down the ecosystem. I may not like the decision, but we should probably make the best of it and start working on/around the most annoying things about systemd. They seem willing to accommodate at least on cosmetic things like ISO dates.
  5. With that in mind, my preference would have been “We will adopt systemd iff a series of ecosystem assurances/development projects happen,” but that is unrealistic and (AFIK) forbidden by the Debian process. Especially a move from putting dist configs in half a dozen cryptic paths in /usr (which offend me in a variety of ways) to, giving credit to the merits of the “/usr belongs to the package manager” retcon, /usr/etc the way some of the BSDs use /etc/defaults.
    While we’re dreaming, forcing an interface/adapter to use a syslog in place of journald, or at least an alternative journald implementation with a simpler back-end (graceful feature degradation acceptable) would be great. I’m not even necessarily advocating using it, just that I don’t tend to take software without competing implementations as credible. Perhaps pressure from the volume of the Debian community will make some of this happen.

  6. I will agree with their vote in the “Fuck it, go with systemd, get the uniformity and feature advantages, try to mitigate the misfeatures, and leave as much room for coming back to the decision later if someone succeeds in writing and agitating for something more satisfying” sense.

Even with all that said, I’m a little surprised OpenRC wasn’t taken more seriously, since it is the conservative incremental progress choice – objectively, it is currently more featured than Upstart by most metrics – but the developers haven’t been politicking the way the Upstart and systemd folks have, and their incidentally combined efforts managed to discredit it. It has better portability (already runs on Hurd and FreeBSD) than the other options, and is one of two with a (admittedly, less featured) cgroups mechanism. The latter one is interesting because via some impressive politicking the cgroups discussion was at some point re-framed from “makes use of cgroups” to “uses cgroups in exactly the same way as systemd.”

I’m curious how the procd/ubus/hotplug2 stack coming out of OpenWRT is going to interact with the rest of the ecosystem, I suspect we’re going to see that stack meet midway with systed/dbus/udev and some of the light distros using it and shims even for PC-like applications, which will likely be the next time things get really interesting, barring a couple skirmishes where user-level software dictates the stack to the metal.

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Spring 2014 Impressions

I’ve been terrible about writing things up lately, but want to at least put my semester impressions on the head of the chain of such posts.

One of my overall experiences is that teaching (and also, taking classes outside my typical discipline) has made me much more talky in class.

CS541: Compiler Design/Finkel
It’s a core class in the CS program, but I’m taking it this semester because Dr. Finkel is teaching it, and his classes are always excellent. I believe this leaves only one compilers/programming languages class offered at UK I haven’t taken, and that one is in the math department and entirely not my thing. I’m just shy of qualified to teach this material, so there’s a slightly odd dynamic in which I wait before delivering answers, and Raphi is frequently imposing a cooldown on my responding in class anyway.

We’re building a compiler for a cleaned up, stripped down C-Like language in Java, basically following Crafting A Compiler. I’ve used an old version of Fischer LeBlanc as reference for compiler material and like it better than the others I’ve used, so I figure this should work out well. Thus far, I’m having more trouble getting myself back into the Java mindset (So OOP. Much Type System. Wow.) than with the Compilers material. High expectations based on experience.

CS621: Parallel and Distributed Computing/Zhang
It’s basically a class in MPI. I’m hopeful that having some nice assigned MPI projects to work on will be good for me. There are two problems though: first, I’m afraid it’s going to turn into a linear algebra class that just happens to take place on parallel supercomputers. Worse, the lectures are terrible. The organization is bad. The slide decks are bad. The Englishrish is bad. The quality of response to questions is bad. It may actually be worse than the terrible Differential Equations with Jar Jar Xin class I took as a freshman. However, it is of the form “CS6xx,” and the content is at least in principle something I want, so as long as the projects and grades turn out, I’m happy. Kind of pissed that the crap lecture overlaps the Friday CS BoF and associated conversation.

GS630: Instructional Technology/Rice
I’m having so much fun in here. It basically consists of a bunch of jaded grad students discussing instructional technology for college teaching, largely from experience, lead by a specialist in the area from CELT. Some of the discussions basically go like this. I’m afraid I’m becoming “that guy” in here because I talk disproportionately and occasionally convivially argue with or reference outside material to the instructor, but again, I’m having a ton of fun, and it counts toward my PFF certificate.

GS610: College Teaching Seminar/Worley
I typically don’t post up my beginning of semester impressions post until all my classes have met, but this one doesn’t start until well into February. At some level, I’m pleased that it’s a general college teaching course instead of a department-specific one, I have trouble imagining a full semester in-discipline teaching class that didn’t turn into a myopia reinforcement program. It should be fun, all the GS classes thus far have been.

I’m not teaching this semester, and hopefully will be getting to more research projects with the freed up time.

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Fall 2013 Semester Retrospective

I noticed while writing the pre- post for the new semester that I lost track of my customary semester review for the past semester while I was moving hosting. Pushing it up now.
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SC13 Retrospective

Posting up my notes from SC13 is another thing I didn’t get to during the end of the semester. Remedying now.

The main takeaway sequence from conversations on the floor is as such:

  1. The era of single-core performance gains is already over.
  2. Furthermore, the era of usable single-die performance for MIMD machines is coming to an end.
  3. Therefore, big machines are going to be getting physically bigger… to the point where connection lengths are a problem (everything is Infiniband, and Infiniband doesn’t tolerate long runs well)
  4. There is a LOT of cooling effort to make the necessary density happen – central large fan systems, immersion cooling, closed-circuit water gear, etc.

The other really exciting thing that it seems AMD is going to make it, and more. Their lean period finished when the payoff on the XBone/PS4 came in, and they have a VERY good plan for the next >2 years. It works with the premise above about single-core/die MIMD performance ending, and points in the HSA direction – this is the crazy parts with MMUs so a CPU and GPU can share memory without skew penalty and such. ARM and partners are also generally pointed that way, and have been for some time, though apparently AMD isn’t getting out of the x86 game, but it does look like they are getting out of the fat core game.
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Hosting Move

I’ve just completed a move of this site to a new host, it should be transparent to everyone else – modulo a few brief intervals during the move – so please let me know if anything appears broken. There is also an exciting new feature in that (almost) everything should now be accessible via SSL. Notes on vendors and selections below the fold.

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