Brad Fitzpatrick (brad) wrote,
Brad Fitzpatrick
brad

computers, gym, electronics, etc...

Computer crap...
So it turns 2 out of 6 drives "failed" last night in my web/mail/cvs/dns/* server's RAID-5 array. In a RAID-5 config, one drive can die safely. After the second, there are problems. So after the second died, the filesystem failed and marked itself read-only. Good.

Looking at the logs, the drives timed out and the controller marked them dead. So I forced them back online (filesystem still read-only) so I could backup a bunch of shit before further muckery.

By this time, our hero sherm arrives at the NOC. We reboot the system, he watches the machine fsck, and things seem fine. Only minor corruption. Put a new kernel on the machine containing some driver updates for the controller card, highmem I/O, e100 driver instead of eepro100, etc... the machine had been up forever. Things were old. Then Sherm added two extra drives we had on hand as hot spares.

So now 4 drives have to fail before we have trouble.

The fact that two drives died during the same night makes me think there was something in the kernel holding a lock too long, masking interrupts, and the driver for the RAID controller just didn't get run in time... or something. I only pretend to know what goes on in kernel land. But I can't believe two SCSI disks just went bad that close together... not on a hot-swap backplane where I understand bad signals from one can't interfere with another.

So anyway, left the "dead" disks online and in use. If they do die again, at least those two hotspares will kick in.

Normal crap...
It's Friday night. I didn't go out and do anything fun because I haven't anybody to go out and do anything fun with.

But I left the house! I went to the gym to run & swim. It's so easy to run when you bring headphones and watch TV.

I had the whole place almost to myself... there were only a couple people in there. There was some weirdo in the pool that was swimming laps underwater. I love doing that too, but it doesn't seem like a workout.

Perl/Qt...
I want to play with the Perl/Qt bindings to make my Mini-ITX Stereo component MP3 player interface. Looks pretty complete.

Electronics
I want to learn electronics. Specially, stuff that interfaces with a computer. I'm thinking of little motors with circuitry that can open and close the blinds on all my windows.

I'm thinking like a serial interface with four wires... +12 V (or whatever the tiny geared-down motor takes), clock, signal, and ground. Then I just daisy-chain them all together.

The interface would let me address one at a time, so there's not much current over the tiny wires.

I've looked and my windows and it should be easy to conceal the unit underneath the lip of the top plastic thing. If I couldn't make it small enough, I could buy fancy covers to put over the windows... right now they're pretty plain looking.

Then I write some software to iterate over them all once per morning & night, telling them to open or close. With a delay in there, so only one is working at a time.

Further, I program my Mini-ITX system in the living room to respond to all IR signals it receives, not just the ones for the mp3 player.

If it notices I'm starting to watch TV, it can just close all the blinds that cast a glare on the TV.

When I turn off the TV, it'll check the time and conditionally re-open the blinds.

I figure the circuitry would just involve a simple state machine and timer. The timer moving the state machine from its motor forward and motor reverse steps to "off" after an elapsed amount of time.

(or could I detect the changing resistance from the motor and automatically stop?)

In summary...
I need a girlfriend.
Tags: perl, tech
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