Laptop Hard Drive Crash
The surprising thing is not a laptop hard drive crash, but the rarity with which it happens. When you think about hard drives and what people do with laptops, it's surprising that laptop hard drives don't crash more often. But it does happen. Here are some things you can do to minimize the risk of a laptop hard drive crash, and to recover if one does happen...
What Causes a Laptop Hard Drive Crash?
A hard drive mechanism is an incredibly precise device. A typical laptop hard drive spins at 5400 rpm, and a standard disk is just 2.5 inches in diameter. A little math reveals that a point on the disk's rim is moving at just over 40 miles per hour. Hovering over that speeding surface, less than a hair's width away, is a metal read/write head. Even better, the head is constantly zipping back and forth across the radius of the disk, reading and writing data in different sectors. If head meets disk... crash!
We're talking about a serious physical crash, not just a software error. The head digs into the disk's surface, gouging up bits of the magnetic film that stores data. Anything written on that part of the disk is gone forever. Nothing will be written to that scratched part of the disk again. The head itself, a delicate thing, may be damaged and unable to read or write data anywhere on the disk.
Now think about how you use your laptop. You turn it on and the disk starts spinning with head and surface dangerously near one another. Then you pick the laptop up and carry it, none to steadily, to a wobbly table in a café. Or you balance it on your knees, shifting your position every couple minutes. You close the lid, turn the laptop sideways, shove it into a bag, and let it swing from your shoulder as you walk. Why on Earth doesn't the laptop hard drive crash constantly? The secret is cunning engineering.
Preventing Laptop Hard Drive Crashes
The disk platter is kept stable by cushions of air above and below it. Filters, or valves, in a laptop hard drive's case maintain proper air pressure inside the case even as altitude, temperature, and weather cause air pressure outside to fluctuate. The read/write head is also supported on an "air bearing" while the disk is spinning, but it does land upon the disk regularly.
To minimize the risk of a laptop hard drive crash damaging areas of the disk that contain data, the head is "parked" or rested upon an area of the disk that doesn't contain data when the head is not actively seeking, reading, or writing data. This "landing area" is usually near the center of the disk, which is not used because it moves slowest and reading/writing data from there would be slowest.
Some laptops have a "drop detection" feature, which quickly parks the head when it thinks your laptop is accelerating toward the pavement. This feature is available in Apple MacBooks, and some other high-end laptops from Dell, Sony and other vendors.
Laptop hard drive heads are generally designed to survive at least 50,000 take-offs and landings before the probability of a failure rises above 50 per cent. Therefore the older your laptop hard drive is, the more likely it is to fail in a laptop hard drive crash.
If Your Laptop's Drive Crashes...
Not every laptop hard drive crash is fatal. A head may crash against a bit of dust on a disk without destroying any magnetic film. Friction from such a very brief rubbing heats up the head beyond its operating range, and the head shuts down temporarily. But it works again when it cools down.
Sectors of a hard drive disk damaged in a laptop hard drive crash can be detected by the operating system's "check disk for bad sectors" function and marked "do not use". Then it's safe to keep using a slightly damaged laptop hard drive. To run a check for bad sectors in Windows:
- Click Start then highlight My Computer to show a list of available drives.
- Right-click on the hard drive you want to check and select "Properties".
- Click the "Tools" tab and then click through the "error-checking" options.
There will be an option to check for bad sectors and attempt to repair them. If you enable this option, the disk check will take quite a long time during which you will not be able to use your laptop. But you will end up with a disk whose bad sectors are marked "do not use".
The most vulnerable moment for your laptop is when it is shutting down or powering up. A lot of reading and writing of data occurs during these events and a laptop hard drive crash can be disastrous. When you close that laptop lid, wait until the disk activity light goes out before moving the laptop. Don't power on your laptop while it's in motion.
Do you have a comment or question about laptop hard drive crashes? Post your thoughts below...
This article was posted by Bob Rankin on 3 Jan 2010
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Article information: AskBobRankin -- Laptop Hard Drive Crash (Posted: 3 Jan 2010)
Copyright © 2005 - Bob Rankin - All Rights Reserved