Archive for February, 2008

Ubuntu RAIDbox: Part 1

Friday, February 22nd, 2008

I needed a RAIDed NAS box that I could rsync to for backing up Linux filesystems. While there are commercial offerings for around the same price, none of them provided native Linux filesystems or allowed SSH access and/or rsync, so I decided to roll my own. This is one way you can make a cost-competitive and low-power RAIDed NAS box in Ubuntu that does ssh/rsync, nfs, and samba. All prices listed are approximate, since I bought more than I needed initially (see below for explanation), but prices do include shipping.

You can probably do it cheaper if you have different requirements. I wanted to reduce the number of moving parts and keep power consumption low, so I went with a passively-cooled mini-ITX motherboard and a CF boot disk. You could easily save about $300 by using more conventional motherboards, but keep an eye out for how much it costs to run the box constantly. My design only has 6 moving parts: 4 SATA HDDs and 2 cooling fans for the HDD enclosure. When off, the power brick consumes 4W (there are likely better models available). On boot, it spikes to 133W while the HDDs power on. At idle, it consumes 67W, and when the RAID is under heavy access, it consumes 77W.

Once all your parts are in, assemble the system. The only tricks involve the power converter board and the hot-swap enclosure. Stick the unprinted part of the power converter motherboard into the PCI Express slot on the motherboard, to keep it away from metal. I also recommend that you attach your enclosure’s topmost SATA drive slot to SATA connector 1 on your motherboard, following the progression down to the bottommost SATA drive slot connecting to SATA connector 4 on your motherboard. This way, if, say, /dev/sda1 fails, you’ll know it’s behind the topmost door in the enclosure.

(*) I ordered more parts than I needed to, and if I avoided the waste with a second RAIDbox, I think the price would be closer to $900. Specific areas of waste were due to cabling and necessary PSU upgrades.

Posted in Technology | 1 Comment »

Chimerism

Thursday, February 21st, 2008

Chimerism is the fascinating state of a fully-formed organism having two distinct sets of DNA.  Basically, during development, multiple (usually just two) zygotes fused and developed into a single embryo. The allocation of the DNA can happen at a high level, such as the top half of the body is DNA1, and the bottom half is DNA2. In addition to, or instead of that, the DNA allocation within individual organs can be a fairly even mix of the two sets of DNA or it can be split essentially down the middle.

The incidence of chimerism among humans is estimated to be very low, but here’s the spooky part: Consider how rarely people would ever get a DNA test to see if they had more than one set of DNA. Maybe you are a chimera and don’t know it.

We have technologies to test for known genetic diseases, but if you’re a chimera, you might provide a mouth swab to test for a disease, and get a negative result, except it’s only negative for that set of your DNA. Maybe the other set of your DNA has the bad genes but wasn’t tested. False positives could occur, too, of course. I also wonder if chimeras could be vulnerable to compound diseases that involve the two sets of DNA interacting in an incompatible way.

As we enter an era when DNA testing for medical and legal purposes seems only to be on the rise, it’ll be interesting to see if chimerism is discovered to occur at much higher frequency than previously estimated.  If so, chimerism may need to be the first DNA test done before doing any further DNA tests on an individual.

Posted in Medicine | No Comments »

A Note to HD-DVD Owners

Sunday, February 17th, 2008

<Nelson>Ha ha!</Nelson>

Posted in Humor, Technology | No Comments »

Stigmata and Demonic Possession

Thursday, February 14th, 2008

My understanding of the phenomena is that they only seem to happen to Catholics.  If they do happen to other Christians, they do not happen in nearly the same frequency as with Catholics.  They also seem to not happen to non-Christians at all, as far as I know.  So what does this mean?

If the phenomena are real, it implies that Catholics are uniquely vulnerable to demonic possession and more likely to be given Jesus-like wounds.  What would let demons more easily possess Catholics?  Why would Catholics be chosen to receive stigmata?  Why don’t all Catholics realize they’re in such danger?  Why do the same things not happen to everyone, or at least to non-Catholic Christians?

If the phenomena are fake, it implies that some elements within Catholic culture are more likely to believe in things like demonic possession and stigmata, otherwise the phenomena would be classified as mental illness and/or self-mutilation and/or Munchausen syndrome, be treated, and never be talked about as supernatural.  Why would some Catholics tend to believe supernatural explanations for these phenomena?

I  don’t have an answer, so I’m curious to know what the rest of you think.

Posted in Culture, Philosophy, Religion | 12 Comments »

Warranty Madness

Wednesday, February 13th, 2008

I got a deep fryer for Festivus and just hooked it up on Sunday, upon which it immediately made a loud “pop!” noise and blew the breaker it was on.  After much troubleshooting, I determined that the electronics module had sacrificed itself in the name of some unknown cause.  This particular model is modular, and the electronics module is a small part of the overall unit.  I called the manufacturer, T-Fal, to return the defective bit under warranty, and I was told that the warranty “only covers the entire unit, not individual components.”  I asked if the rep realized the absurdity of that, since warranties are usually restrictive in the opposite direction.  I was told, though, that if I wanted to replace just the failed component, I could always just buy one.  Nice!

The reason I was given for the whole “all or nothing” stance is that they’d be doing what amounts to integration testing on the whole unit before sending it back, and if they couldn’t fix the problem, they’d send me a new unit.  Thanks, but I think the mechanical components are fine, based on my previous assembly, and all I need is a replacement electronics module.  My end result will be the same: a working unit.  The bottom line is that I just don’t want to pay more than I have to for shipping to get it.

I’ve been on the other end of this warranty issue, too, and I use the same philosophy.  On rare occasions when there have been component failures with computer systems that I sell, I’ve always complied with customer requests to just send back individual components.  If I know full well that one stick of RAM is bad, why in the world should I make the customer send a 35-pound computer back just so I can swap it for them?  It’s only when the problems couldn’t be remotely diagnosed or addressed that I’ve needed the entire system back.

A supervisor is supposed to call me back in 1-2 days to either try to convince me why I should pay extra for shipping, or to listen to what I want and make it happen.  In the meantime, let’s all think about what’d happen if your aftermarket car stereo’s warranty required that you send them your entire car so that they could do proper integration testing on a replacement unit, or if your rechargeable battery warranty required you to send them any and all devices you used with the batteries so they could test the replacement batteries.

Posted in Philosophy, Technology | No Comments »

Buying Online: Convenience vs. Security

Tuesday, February 12th, 2008

I run an online store, and one of the features we offer is shipping to an address that isn’t the customer’s billing address. I did this for a couple of years without verifying that the shipping address was connected to the card holder, until some limo driver in Ohio defrauded us and other online stores by ordering items as one of his previous customers. He knew the real billing address because he picked the victim up at his house, and he used his own home address as the shipping address. Unfortunately, not all fraudsters are as dumb as this man, or the problem might weed itself out genetically.

Nowadays, we call the credit card company to verify that the customer’s shipping address is registered as an alternate shipping address with their account. This ensures that the actual card holder(*) has provided the address, rather than just someone who knows the card number and the real customer’s billing address. Ironically, even though I always offer to provide all the information and only ask for a yes or no response on the validity of the shipping address, some credit card companies won’t even talk to me because I’m not the cardholder, citing “security reasons.” It’s for “security reasons” that I’m doing this in the first place. Thankfully, these short-sighted policies are rare.

I know of no way to automate this, and it’s not clear that it’s even possible without each credit card licensee wanting to provide this service and agreeing on a common API(**). This means that the process is not convenient for the store, and it’s not convenient for customers who have no alternate shipping address on file and are asked to add one. Most large online stores don’t go through the pains of manually doing this verification, preferring to combat fraud through some combination of automated heuristics that don’t work all the time, random manual auditing, and after-the-fact actions like litigation. This means that all someone needs is your address and your card information, and they can probably order whatever they want and have it shipped wherever they want. It gets worse when the fraudster lives near you, since it’d pass any distance-based heuristics for guessing whether or not a shipping location is ok.

Think about who could have your address and your card information: cab companies, limousine companies, Lowe’s/Home Depot delivery, moving companies, or a cashier at a restaurant who copied your card information and looked up your address. “But Bob,” you say. “This is FUD! If it’s so easy to get this information, why hasn’t everyone become the victim of credit card fraud?” First of all, lots of people do fall victim to it. Credit card fraud is big business on all sides of the issue. Having said that, there’s a relatively small percentage of people who have access to your full credit card information, since it’s in the best interests of the business owners to make sure they minimize the number of eyes that can see it. I suppose it’s also fairly easy to catch most people who commit credit card fraud, especially when they can’t resist ordering lots of items and helping investigators to narrow down the search, so perhaps the failures of individuals sustain the notion amongst most would-be fraudsters that it’s too much risk for too little gain. It may also be the case that everyone has had someone try to commit fraud using their credit card, but some combination of store action and credit card company heuristics caught it before it happened.

Whether or not you choose to worry about this is up to you, but if you want to help stores out that do take the extra steps to make sure items bought with your card can only be sent to addresses that are associated with you, it’s easy to add an alternate shipping address to your credit card account. Just call up customer service, tell them you’d like to list an alternate shipping address, and they’ll know what to do because it’s far more common than you might have known. Then when people like me go through the manual process of calling up to make sure it’s your alternate shipping address and not some random place where a fraudster decided to hang out and wait, your order will go through without further intervention on your part.

(*) or at least someone who has access to so much sensitive information that they seem to be the actual cardholder

(**) This is one of the rare times when I think government regulation would help.

Posted in Uncategorized | No Comments »

Acronyms FTW

Monday, February 4th, 2008

I learned recently that the acronym FTW usually means “For The Win” and not “Fucks The World” as I had thought. Strangely, the alternate version is very similar in context, but I now know why utterances like “Ubuntu FTW” didn’t quite seem to fit the character of a typical Ubuntu supporter.

Posted in Humor | 2 Comments »