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Computer Voodoo?
jbeaupre asks: "A corollary to 'Any sufficiently advanced technology is indistinguishable from magic' is that sometimes users have to resort to what I call 'computer voodoo.' You don't know why it works, you barely care how it works, but you find yourself doing the strangest things because it just seems to work. I'm talking about things like: smacking a PC every 5 seconds for an hour to keep it from stalling on a hard drive reformat (with nary a problem after the reformat); or figuring out the only way to get a PC partially fried by lightning to recognize an ethernet card, after booting into Windows, is to start the computer by yanking the card out and shoving it back in (thereby starting the boot processes). What wacky stuff have you done that makes no obvious sense, but just works?"
Not sure how it works, but I've saved 2 or 3 hard drives that reported tons of bad sectors with cat /dev/urandom > /dev/hdb and then cat /dev/zero > /dev/hdb and repeating that a couple times. Seems to alleviate all the problems. The drives wouldn't format, and all the data would get corrupted, but after doing that trick, they haven't had a problem (with the longest running drive being 2 years after the fix and still going).
Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
I once had a hard drive that wouldn't spin up if the computer had been off a few days. The only way was turning it by 90 degrees every time before booting the computer.
In my repair monkey days, my shop used to handle data recovery jobs of all kinds. The problems ranged from minor filesystem corruption or unbootable drives to physical damage - heads, and even a bullet through a hard drive (No, I wasn't able to get anything off that one).
We had a variety of methods for dealing with the physically damaged drives that had suffered a head crash, but my boss had a technique he called the 'massage'. A clicking or noisy drive would be rotated around its various axes until the BIOS would recognize it on boot. Sometimes the clicking would stop and he would sit there holding the drive in that position or prop it up to keep it there.
Another method we used was to freeze the drives for a period of 15 minutes to 6 or 8 hours. Sometimes this allowed enough contraction to let the tracks line up again, and we'd get as much data as we could with the drive cold. Once, we even froze a drive between two ziploc bags of water with IDE and power cables hanging out the edge to keep the drive colder longer. It worked!
-- Shade
Technology tips and tricks.
However, after I installed the card, Windows 2000 would crash with the following BSOD:
Annoying as heck-- somewhat expected from a cheap network card.
So one day I was wat home downloading Fedora with bittorrent--- my DSL connection was maxxed out. There was too much interference on the line, so I hit the little 'channel' button to switch to a different channel.
As soon as I hit the button on the phone -- *boom*, the computer threw up the Blue Screen of Death. ANd sure enough, I reboot, hit the button on the phone-- and *boom* -- Computer crashes again.
I have since replaced all of the D-Link cards with cards from other manufacturers.
"Can of worms? The can is open... the worms are everywhere."
Actually, some people laugh at that, but I have the same thing happen. I remember a couple of years ago, I convinced a friend of mine to try switching from Mandrake to Suse on his laptop. Chatting with him on the phone, he complained that booting up the system was taking 15+ minutes. I drove over there to see if I could possibly diagnose the problem (he had been using linux for a while, but was never really much for sysadmining). I walk over, he boots up the machine, it boots up very quickly and runs flawlessly. Tried a couple of more times, same quick bootup. After I went home, he tried rebooting and ran into the same problem. We were both dumbfounded for quite a while, until I finally worked out that it was because when he had been using it, he was sitting in his living room, and it had hung waiting for eth0 to time out, but when I came over to look at it he put it in the docking station and plugged in the ethernet cable.
I've seen other situations like this. Many times, it's because the user is doing something they know is stupid/they shouldn't be doing, and with a techie looking over their shoulder they don't do it.
Famous Last Words: "hmm...wikipedia says it's edible"
Got to love old school hacking
I have mod points and I am not afraid to use them
True, and throwing out equipment fried by lightning doesn't hurt, either. Seriously, what kind of questions are these? Hardware doesn't work? Isolate it and replace it. Other than freezing an old hard drive to free up bearings to get data off before you throw it out, it's not worth the aggravation.
Of course, as far as real Computer/Equipment Voodoo is concerned, there is always the Heisenbug. Just had a mechanical version of this today, the Bayer tech has spent 3 days on a machine to isolate a pump problem. To see the pumps, you have to open a panel either on the side or the front of the instrument. The past 2 days, he was working on it through the front, and the problem didn't occur. Today, after being called back because it happened again, he opened the side panel to watch it, and accidentally bumped the front panel while he was looking at it. As soon as the front panel closed, the problem occurred. It turns out that a zip-tie that holds some tubing from the pumps together was caught on the front panel, and when the panel door closed, it pulled on the zip-tie, which pulled on and pinched the tubing, causing a pressure sensor to throw a fault.
--That's the point of being root, you can do anything you want, even if it's stupid.
Just today I turned my computer on after leaving it on hibernate for a week. The "thaw" as I guess it could be called, failed (the computer hung before showing anything useful) so I rebooted. Windows starts up fine and then tells me my hardware has changed and I need to reactivate Windows. Except my hardware hadn't changed since the last boot (over the course of owning this computer, admittedly it had changed a lot). Oh wait, I can't activate over the Internet anymore, I've installed it too many times on the same machine, I have to call Microsoft, speak a 42 digit number slowly into the phone, get put on hold, be told I spoke the number wrong, put on hold again, read part of the number to a person, and then type another 42 digit number read to me over the phone. Then my computer will work again.
I used to have a Performa 5200 back when I started college, and if you're not familiar with the machine, it's arguably the worst Macintosh ever made. Ever. The only thing it excelled at was displaying grainy TV on the TV tuner card you could get for it.
Read that second link for all the gory details of why the follow scenario works, and you'll shudder.
I used to note in college that when doing particularly fast FTP transfers that saturated by 10-Base-T card that the machine would often lock up within a minute of starting the transfer. For months, I fiddled around and noticed that if I was actively working that this didn't happen. Eventually, I found the article I mentioned and realized that if I kept moving the mouse constantly, the machine wouldn't get in whatever weird state locked up the machine and I could finish my transfers. That's right -- to run FTP (or any other sustained, saturated transfer), I had to sit there moving the mouse in circles through the entire transfer.
Essentially, the "Left 32" bus described in the article was shared by the 16-bit Apple Desktop Bus (for mouse and keyboard) and the 16-bit networking card (as well as audio and the 8-bit SCSI controller). So long as I kept interrupting the bus with input from ADB, the networking card was unable to flood the controller that had to make sense of all the different bit-widths and clock speeds between the various busses hanging off of it, and the machine wouldn't lock up.
Now how's that for some serious computer voodoo?
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
Nostalgia - blowing on the Nintendo game cartridge.
Why in God's holy name does Windows fail to boot one time, and then boot successfully the second time?
Hah. I had something close to that one. A friend's Windows XP Home system. Boot it up, runs fine for about 30 seconds, then locks up hard. Reboot it, works fine for as long as you like. Next time you boot it up, locks up after about 30 seconds. Reboot, works fine. Lather, rinse, repeat.
I booted it up off a Knoppix disc and ran a bunch of hardware tests -- nothing. And no problems with locking up either.
Back to Windows -- same thing.
I eventually realized the pattern: after a clean Windows shutdown, it would lock up 30 seconds after the next boot. After a dirty shutdown (e.g. power cycle or reset button), it would boot up fine. Obviously the Windows shutdown was leaving something in a funky state for next time. Beats me what.
I told my friend she had the choice of doing a re-install and keeping fingers crossed, or always shutting it down with the power switch, or moving to Linux. I don't recall what she did beyond passing the box on to her kids because she'd already got a new one for herself.
-- Alastair
My dad works for the Arkansas Washington County Road Service, and he is something of a computer nut, so he would 'recover' the computers they were throwing out. I was pretty profoundly poor and also a computer nut, so I would take some of the stuff off his hands.
Anyway, I used to have three or four MFM hard drives in various states of disrepair. (I think they were 40 *meg* hard drives, but I only had a controller to control up to 20 meg, to give an idea how old this hardware was.) One by one they died, until finally only one was left. When it gave up the ghost, it would spin up, then immediately spin back down. I dug into it and found some connections I could short across while it was spinning up and then break the connection, and it would keep running. I was too poor to want to go spend $1 on a pushbutton, so I just had two wires hanging out of the front of the computer that I held together while booting the PC. I ran it that way for over a year...
A non-computer story, but more interesting one, is of an old Ford Escort I used to have. The starter went out on it, and, again, I was poor, so I dug into it. I finally figured out that the relay was kicking out too far and shorting out against the housing, so I duct taped a kitchen sponge to the inside of the relay housing and put it back together. I never had a problem with the starter again for the 2 years I had the car.
That same car later had the fuel pump go out. When it went out, I asked my stepdad if I should check to make sure the pump was out instead of a wiring or power problem, and he said nah, it's the pump. So I bought a replacement - it didn't help. So, I hunted around under the hood until I found some leads that were hot when the key was on, but not when it was off, and I used ties to secure an extension cord from the leads to the fuel pump. The car ran fine.
That was in the summer. When winter came along, one day I needed to defrost the front window as I was driving down the road. I flipped the vent from dash to defrost, and the engine stopped running. (I was doing 50 mph down the road at the time.) I flipped it back to vent, and the engine started right back up again.
Somehow I had found a wire that only gave power when the vent was not on defrost. I never fixed it, just kept the inside warm enough that it didn't frost over.
Now I'm a software developer and not poor. I virtually never fix (or jerry rig) anything myself, other than software and the occasional computer hardware issue.