top-quark.blog

you'll never know how nerdy i really am

Microcenter had an ad for cheap USB flash drives. Something like $10 for a 1 GB. I'm completely in love with the information density they offer, as well as their overall ruggedness, so I went ahead and grabbed a couple. They had two flavors - a Kingston DataTraveler 1 GB and a Microcenter-branded drive, with U3.

It started with wanting to find out which of the two drives was faster. Using XBench, a benchmarking suite for Mac, I went ahead and ran some hard drive benchmarks. The results were pretty comparable, with the Microcenter-branded drive coming out a touch faster on uncached writes. (results below - just you see)

Then in the process of trying to get rid of the U3 "feature", I re-found that OS X's disk utility is a rather powerful piece of software. You can, among other things, create RAID arrays from a variety of different devices.

Sooo...

Plug, plug

Click, click

So more benchmarks were set up with the new flash drive RAID, and the hard drive on my laptop. The results, with the original data, are below:

Really, the whole playing around with drives and RAIDing was just shits-n-giggles. What really scares me is that I automatically started putting numbers into an Excel spreadsheet, pivoting out results, and making charts. I was halfway through specifying chart series before I realized what the hell was going on. Working in the commodities trading industry has done terrible things to my apathy.

Results interpretation is sort of a repeated exercise in "duh", but the most obvious point is that the hard drive kicks the crap out of the flash drives in writing. What's also "duh", but notable, is that while the hard drive took a hit going from sequential to random large block reads, the flash drive (and flash drive RAID) performance was more-or-less unaffected. Surprisingly, the 256k block read performance on the flash RAID array exceeded the hard drive in both sequential and random cases.

Putting it all to practice, copying over XVID movies to the flash raid array allowed for skipping around the movie without playback delay, where the same files on the hard drive required some time to get going after moving. I imagine this could be useful for video editing, or perhaps some database access situations. There's the usual worry about the life of NAND flash memory, but that doesn't really apply to reads, and it's now often stated that wear-leveling has resulted in flash drive lifetimes comparable to magnetic disks.

Overall, what really sticks out in this case is a kind of general engineering observation, in the implementation of systems manifesting dichotomy. Rather than utilizing one approach or either, igniting numerous holy wars en route, the solution is often to utilize a hybrid approach. The most solid examples coming to mind now are CISC/RISC (Micro-ops), and the essential data storage dichotomy of fast+small and slow+big (caching).

The key in any of these is to allow for an offset between the approaches, such that the weakpoints of one side exactly coincide with the strongpoints of the other. The situation illustrated with the comparison between the flash RAID and the hard drive shows a dichotomy that could be exploited accordingly. An interface could be implemented where random reads could be directed to the flash component of a drive, and sequential operations directed to the magnetic drive component. This segregation could be realized by statistical examination, or just with some sort of miniature tournament model, where the interface issues commands to the flash and magnetic components, and waits for the first component to return the result of the operation.

I know it's livejournalish to post IM conversations, but I appreciate harsh truth:

[22:34:59] me: why am i doing this
[23:30:54] friend: why are you doing this?
[23:54:52] me: I don't even know
[23:55:22] me: but I do know that if I'm gonn do uncached random reads, a ghetto flash raid array is wonderful!
[00:06:55] friend: why can't you just have normal hobbies?

Edit: I'm never as clever as I wish I were:
ipod shuffle raid
hybrid hard drives

Java, OS X Terminal, and Unicode - a Sordid Tale

I'm pissed off, and I'm not sure who or what to blame.

See, right now, I'm trying to build a front-end to the UNIHAN database, which I've found to be profoundly useful for my East Asian language research; specifically the fact that it contains Tang Dynasty-era pronunciations for quite a few CJK (Chinese/Japanese/Korean) characters. The Mandarin, Japanese, and Sino-Korean pronunciations are also very nice to have. Unfortunately, the database itself is a massive UTF-8 flatfile, keyed by a character's hexadecimal UTF-16 codepoint, so it's not the easiest thing in the world to use.

So I'm using Java to make an application to allow me to type in a Han character, and get the UNIHAN data. What pisses me off, though, is the way that (Java/OS X/OSX's Terminal) handles unicode output. It's messed up as hell, and I don't. know. why.

Here's an example. Suppose I have code that looks like this:

System.out.println("你好");
System.out.println("\u4f60\u597d");

The first println works fine, and outputs the characters fine to OS X's Terminal. The second println, using the UTF-16 codepoints for those two characters (U+4F60 and U+597D, respectively), prints out two question marks. Cut-and-pasted, straight from terminal:

你好
??

I shit you not.

This isn't exactly something anyone I know can help me with, either. The most helpful answer I've gotten is that there're some very rare variant characters that have a codepoint associated with them, but no glyph representation in a font. This I knew, but there's a slight issue with that explanation. Namely, that the characters "你好" are roughly the Chinese equivalent of "hello".

Well, that, and the fact that the characters printed out just fine ON THE LINE RIGHT ABOVE.

So I don't know whether to blame Java, OS X, or Terminal, all of which are purported to be unicode-friendly. Actually, I think there's a strong chance that it's my fault, but we can pretend I didn't admit that. What I may just end up doing here is to declare a "screwit" situation, and just jump to the Swing app I was thinking about making, since that supposedly solves many issues.

Grado SR-60

Being on campus for 14 hours a day is not particularly fun. Lately, a large portion of that time's been spent with a pair of cheapie ipod-style earbuds stuck in my head. For various reasons, mostly my irrational disinclination for going deaf, I've decided to stop using earbuds. My replacement led me back to a set of headphones I'd had once, and really enjoyed - the Grado SR60.

Some very basic research on the net provides a treasure trove of reviews about the SR60. It's the darling of value-oriented sound enthusiasts, and a common infection vector for audiophilia. I won't really go into a huge analysis of my experiences: after about 48 hours of moderately loud break-in, they sounded excellent. My only complaints are that bass is a little weak, the upper end is a little lively ("bright"), and that there's not a lot of sound isolation, for either the listener or the public. These are expected, if one reads the reviews.

A pair of airline socks valiantly gave their lives to the cause of better sound.

Their sacrifice was certainly not made in vain; the socks improve every shortcoming of these headphones. Bass response is (imo, greatly) improved, with only a trace of muddiness. I think this very slight muddiness might be due to the choice of material; a less "fuzzy" sock might have crisper response. Also, rolling them tighter would probably be an improvement (I'd do it, but then I'd need to resew the stitches holding the "rolls" together). Sound isolation is also much improved over my original pair of "quarter-modded" (i.e., quarter-size hole removed) foam pads. The last major improvement is to comfort; I don't find the stock "comfy" pads to be as offensive as some do, but my last pair of decent headphones had earpads surrounding the entirety of the ear (circumaural), versus the "on ear" (supra-aural) design of the original foam pads on the SR60. Tradition won out, and I find that these new pads are much more comfortable than the stock supra-aurals.

More mods may be coming; I'm pretty sure I'm going to rewire the headphones with cable that's thinner. At 3/16 of an inch, the main cord on these is pretty hefty; enigmatically, the "branches" coming off the y-connector feel cheap and thin.

When I get around to opening up the headphones for recabling, chances are good that I'll be doing a couple other mods. Offhand, I'm thinking about adding jacks to the headphones, and plugs to the cable, so that I won't kill my phones if I stand up with my cable underfoot. I'm also thinking about making the wire connection to just one side, and running the wire up through the headband for the other side. Some audiophile nuts I talked with tried to convince me that this would degrade sound quality, on account of the signals being out of phase, due to the small amount of extra cable run.

Sitting down with my calculator, though, I figured a worst-case scenario of about 2e-4 radians offset. That's 0.0002 radians. If there's nothing else you should learn from this short excursion into the world of higher audio mania, it's that the term "audiophile" is a synonym for "sucker".

With profuse apologies to toshi, whose photographic obsession with desaturation has "colored" me. Ha ha.

Nice surprise

I'm often in the habit of ignoring my aquariums when my schedule gets into a bind. While usually this has negative effects, such as burnt-out powerheads, stunted plant growth, fish jerky, etc., the neglect does occasionally yield something interesting.

Today while getting my laundry done, I noticed something unusual in my ten gallon soil substrate "natural" tank.

Despite the fact that the plants have a virtual monopoly on that tank, I haven't ever seen Dwarf Sagittaria flower before. There's a half-dozen others in there, too, in various stages of bloom and decay. I suppose it qualifies as something of a "duh!" remark, but submersed culture almost never sees flowers develop in my tanks; it's only when I allow the water level to fall (intentionally, of course) that I see the plants making effort in sending up flower stems. Anubias, Crypts, Bacopa, Anacharis, a dozen other kinds of plants all show the same behavior. Water level drops to where the leaves are just under the water surface, and they send up flowers. Mimicking nature, I know.

There's two bits about the hobby that this emphasizes; for me, at least.

First, that aquatic plant cultivators that limit themselves to strictly submersed culture are depriving themselves of one of the more interesting aspects of the hobby. Yes, I appreciate neatly-trimmed lawns of Riccia just as much as the next guy. Yes, I know it brings one dangerously close to the completely pedestrian realm of terrestrial plants, but who're we kidding anyway? It's not like the "aquatic" plants we see exist only in the bottom of several inches of water; there are wetness cycles in nature, and these plants do sometimes get dry.. This fact being emphasized by the number of bog plants in the hobby sold to unknowing aquarium keepers.

The second point is the mega-tech with water column fertilization is a nice approach to getting tremendous growth, but soil substrate techniques are definitely effective. If this tank had been one of those CO2/PMDD daily water column dose setups, I'm not sure the water level would have fallen this far without the tank rendering itself into a massive bowl (cube) of cellulose soup. With soil, you have a pretty decent supply of macros and micros in the substrate, so there's something of a buffer for neglect. Not that you can't use CO2, PMDD, regular DD, and other wonderful bits of the modern world in these setups...

Incidentally... all the dwarf sag in that tank originates from a single plant that sent out runners to colonize the tank. Will the flowers even be able to pollenate, given that the plants are all clones? I remember my BigAss(TM) Echinodorus rhizome clones having viable seeds after sending up flowers.

$7 laptop stand

So, several months ago, when I first got my new laptop (yes, the ibook), I went traveling across the net to see what sorts of gimmicky and expensive crap I could buy for my system. Though intrigued by its clean design, high quality, and practicality, I was fracking appalled by the $90 pricetag of this particular stand.

It is undeniably nice. But, I hate apple yuppies, and... I'm a DIY-er.

Anyone with a bit of constructive ability should be able to figure this one out. It's just a bunch of 3/4" PVC with associated fittings, totaling about $7, with plenty of material to spare. If you had a PVC bender, you could build it even cheaper. While it does wobble ever-so-slightly, it's not irritating, and is largely mitigated when you keep your palms on the rests, or use a separate keyboard. The wobble could well be my fault, though, since I haven't actually glued mine together yet. If it *really* bothered you, I suppose it could be filled with sand, or, gods forbid, you could modify it to have additional structural elements.

Aside from the obvious benes like clearing up desk space, it's helped to keep the system a lot cooler. I haven't heard the fan kick in since I built it, which I'm sure the internals appreciate.

There's an ergonomic benefit, too. Your average computer hobbyist/professional has a really fantastically bad slouch. I say this from a position of authority, having once had such a slouch, until the last year or so. Between elevating all my desktop displays on a hutch, and this laptop stand's similar effect, my posture's improved dramatically. Not that the chin-up bar and strenuous physical conditioning didn't help, but the continuous effort typically has more effect than the sporadic. If you were going for that angle, it would probably also help to have a table-level keyboard to prevent shoulder scrunching.

For my apple-loving readership, I know all this practicality talk's irritating. In not so many words, then, what is it that makes this cheap stand better than the premade hoi polloi?

It's white.

Racists, the lot of you.