Hard Drive Crash
Opened up a particularly spectacular hard drive crash
“Can you get my files back?”
“No.”
Inside your desktop computer is a data-storage device called a “hard drive”, so named because it stores data on a spinning aluminum platter (as contrasted with the mylar data-storage surface of a “floppy disk”). These platters spin 60 times per second or faster and are mirror-shiny, perfectly flat as a telescope mirror is perfectly curved. They are usually electroplated with a cobalt alloy because aluminum cannot record magnetic impulses.
The data is written onto the platter by a tiny electromagnet that floats a couple millionths of an inch above the platter at the end of a head actuator, which positions the head above the precise location of the magnetic imprints. This electromagnet is called a “Read/Write head”. Normally it never touches the platter when the drive is turning.
When drives fail, they usually make a clicking noise known as the “Click Of Death” as the drive controller (the circuit that steers the actuator arm) seeks but cannot find track zero. Another failure mode is a “Drive Crash”, where the head literally crashes into the moving platter, grinding away the surface (and your data).
This drive made a horrible screeching noise in operation as the R/W head ground its way into the aluminum. Usually the platter surface is intact except for the inner-most track (track “0”), but in this drive there was a bonus; the head kept seeking after the crash occurred, grinding up the whole surface of the disk. The drive was full of aluminum powder.
Notes:
By the way, if you can get ahold of an old hard drive, take it apart. They’re very interesting devices. The platters are so perfect you can reflect a visible spot of sunlight a couple blocks away. Hard drives contain the strongest magnets most people will ever see - usually a neodymium alloy with cobalt, iron, and/or samarium. (and strong enough to stick a magazine to your refrigerator). The ring-shaped spacers between stacked platters are (like the platters themselves) machined to absurdly fine tolerances - for some reason it is inspiring to handle such precise parts.
Shown in this picture is the interior of a normal hard drive. Upper-center is the data storage platter, which rotates around the main spindle. Extending into the platter area from the lower right is the actuator arm. At the upper tip of the arm is the read-write head. At lower-right is the “voice-coil” portion of the actuator (where the super-strong magnets are located), which moves the arm around the actuator spindle to locate the read-write head on the platter surface. Not shown is the drive motor and control circuit, as they are on the other side of the drive.
Great close-up picture of the Read/Write head.
Plus, that has got to be the coolest self-portrait shot ever.
Posted by MrsDoF on 10/17/05 at 08:55 PMHere is a user point of view for Hard Disk Crash
Posted by Abster on 10/18/05 at 02:18 PMYou can use Gmail to back up your hard drive, too.
Posted by The Bo$$ on 10/18/05 at 05:40 PMGmail backup - cooool! Luckily this particular drive (which crashed about two years ago and I just ran across it while cleaning up my office) was a lab machine and the user only lost a few files.
The biggest problem most users have is not lack of backup options but lack of understanding of file management. They scarcely understand what a “file” is, let alone where their files are or what “backing them up” would entail - as Abster’s cartoon aptly shows.
I hope by publishing pictures and explanations it may help more people understand what a hard drive is and that they can fail.
Posted by george.w on 10/18/05 at 09:29 PMNice explanation and description of hard drive mechanics. I’ve been lucky with only one “click of death” event. Now that I’ve said it, one of my hard drives will undoubtedly crash tomorrow…
Posted by Buridan on 10/19/05 at 03:06 PMI have a question. On the bottom of this page is some info: times viewed, page rendering speed. Those are self-explanatory. What does the last bit indicate? In this case being “38 queries executed”
oldgreek-visitor from SEBPosted by oldgreek on 10/26/05 at 11:35 AMHere’s an old classic on the subject
Yesterday—The Backup Song
Yesterday,
All those backups seemed a waste of pay.
Now my database has gone away.
Oh I believe in yesterday.
Suddenly,
There’s not half the files there used to be,
And there’s a milestone hanging over me
The system crashed so suddenly.
I pushed something wrong
What it was I could not say.
Now all my data’s gone
and I long for yesterday-ay-ay-ay.
Yesterday,
The need for back-ups seemed so far away.
I knew my data was all here to stay,
Now I believe in yesterday.Posted by Mark on 10/28/05 at 06:01 AMDo you mind if I upload this image to Wikimedia, DOF?
Posted by The Bo$$ on 10/31/05 at 11:30 PMOldGreek, this is a case of “Les is more” as in… Les Jenkins over at SEB could answer that question better than I could. As I understand Expression Engine, the page does not exist until you call for it, and then it is assembled from a database; hence the “38 queries executed”.
Buridan; good luck! I don’t think hard drives are listening to us, so you probably didn’t jinx it. (OK, I’m whistling in the dark!)
Mark - good one! I’m putting that one in my next “email from the geek” to our department; thanks.
Bo$$ - you’re welcome to the picture (but now I wish I’d done a better job of making it!)
Posted by george.w on 11/01/05 at 09:06 AMI looked in my culch-pile, and still have that drive. Here is another attempt at a picture:
I have passed this drive around a couple classrooms while teaching computer support. Students like to see the actual thing rather than hear me yap about it.
Posted by george.w on 11/01/05 at 03:59 PMI opened up a old 883mb hard drive from a pentium 1 computer that crashed, there was a ring around the edge, and there was a lot of aluminum powder in there. The drive was making the click of death, and was vibrating like crazy.
Posted by Logan Neidlinger on 07/16/07 at 11:24 PMits actually great to find out how things worked, most of us just simply turn our computers on, its actually nice to know how one works
Posted by steve on 10/30/08 at 10:01 AM
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