A condition that can prematurely cause failure in hard disk drives.

After many billions of revolutions (a 7200rpm drive will rotate 4320000 times in a 10 hour session) microscopic pieces of the alloy that makes up the spindle will shear off and cause friction in the mechanism. When enough of these particles build up, the drive can have trouble coming up to speed. It may appear to be dead.

The easiest fix is to thump* the device on it's flat side with the heel of your palm and replace. You might have to do this every few months, but it can increase the life of the drive for quite some time.

*ensure that the drive is powered off and spun down, obviously.

Actually, the term stiction was invented for a particular problem with a particular set of hard drives. Back in around 1990 (gah! I'm old!) a several-month run of 80-megabyte internal 3.5" drives from Quantum began to exhibit a particular design flaw. Apparently, a lubricant used inside the drive could (and in many cases, did) drip down onto the spindle where it passed through a metal plate. The droplet would then congeal slightly when the drive was turned off and had cooled (drives operate at fairly high temperatures). Hard drive motors are designed for extremely high speed and not for any variation in resistance; as a result, the motors didn't have the torque required to 'break' the bit of lube and spin up the drive.

This problem might not have come to the attention of the computing world to the level it did had not one of the largest customers of those drive mechanisms been Apple Computer, to put in its Macintoshes. Mac users, as the world has found, are a particularly outspoken bunch with a strong sense of community, and eventually, a recall order was issued such that dealers would replace such drives free of charge if they were brought in.

The most common placement of these units was in the Macintosh SE, SE/30 and Mac II machines (II,IIx,IIcx). As a result, many Mac-savvy tech support personnel got used to saying to clients "Okay, try this. You have an SE? Reach around the right side of the machine, just below the level of the floppy slot, and give it a good thwack with the heel of your hand. Then turn it on and see what happens." (pause) "Great. Yup, I'm psychic - I could hear your Mac calling for the massage. Really." Or: "You have a Mac II? Okay, pick up the right side of the machine about three inches and drop it back onto the desk. Now boot it."

Many users, I found, gleefully accepted the instruction to smack their computer. Their relief and almost smug joy when it actually worked made the whole debacle easier to bear.

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