Has anyone ever successfully revived a hard drive after it started making that dreaded metallic clicking sound?

January 27, 2006 11:55 AM

Has anyone ever successfully revived a hard drive after it started making that dreaded metallic clicking sound? I've already tried whacking it, and putting it in the freezer. Any novel ideas out there before I add it to my paper weight collection?
posted by moseymose to technology (6 comments total)

To answer your first question, no. I also put my freshly-whacked Maxtor into the freezer and all I got ... was a cold broken hard drive.

Some local repair place offered to retrieve my data to the tune of $1000 and I still haven't stopped laughing.
posted by Makebusy7 at 11:59 AM on January 27, 2006

Yeah, I've worked with PCs for years and have never had a HDD come back to life after failing. If you need to get something off of it, you're likely out of luck unless you want to pony up the big bucks for a service like OnTrack.
posted by BigLankyBastard at 1:15 PM on January 27, 2006

The freezer trick works for some scenarios, but not all. Failed reads and writes, or a generally inaccessable drive, sure. But there's usually no coming back from the dreaded clicking.
posted by CrayDrygu at 2:45 PM on January 27, 2006

Yes, I have.

There are two things you can do. One is replace the logic board with an identical hard drive's controller. That may or may not work. Usually not.

The second thing you can do is crack open the Winchester cavity and swap platters with an identical working drive. This operation is not for the meek, as it requires a makeshift cleanroom. Any dust, spittle or phlegm that gets on the platters means lost data, so you have to be very careful.

This is what you pay those companies $1000 for.
posted by Civil_Disobedient at 3:53 PM on January 27, 2006

I once had a hard drive clicking simply because my power supply was busted. So, check that.
posted by TheOnlyCoolTim at 4:40 PM on January 27, 2006

The Click Of Death is actually the Whack Of Death.

There are two motors in a hard drive. The first is obvious -- it's the spindle motor that spins the platters. In the very old days, these were awesome 1800 or 2400 rpm self-sync DC motors. These were cool toys. Later ones were 3600 rpm DC motors, with external sync via hall effect sensors -- 3600rpm, you wonder? SImple. 60 rotations per second, made the clocking easy. Modern ones, spinning up to 15K, are very simple DC servo motors with very, very complicated controllers that sense the speed via back EMF on the motor coils. Very trick, and useless in other projects, but once you've got the software, really cheap and fast.

The "Freeze the drive" trick is for problems with the spindle motor. A shorted coil in a motor keeps it from spinning. Freezing it can move the coil such that it isn't shorting, and the drive spins. Whack the drive fixes stiction -- a bearing, or a head, sticks to the platter, and it doesn't have enough torque to spin the drive. A whack breaks things lose, and the motor can spin the disk.

That's not the problem here.

The other motor is the head positioner. In the old days, these were stepper motors, and the stepper on the ST 3040A was legendary -- guys would pray this drive would die so they could steal it. Steppers, however, are only so precise and fast, so modern drives use voice coils to quickly place the heads just so. Originally, there would be either a "wedge" on one of the platters that had tracks that the heads could use to quickly find tracks, or an entire side of a platter was used for dedicated information about where the tracks were. Modern drives use what's called "embedded servo" information -- the information about where the tracks lie is underneath the data, so you don't lose the capacity of a wedge or dedicated servo.

This leads to the Whack Of Death. To move the heads, a current is sent in the voice coil, and the heads count the tracks as they cross the servo lanes. So, to move 50 tracks in, the coil charges, creating a magnetic field, and since it's stuck between two really powerful magnets, it moves, and fast. The heads count tracks until they reach 50, then the current stops charging, and the heads stop.

What's the whack? The whack is the heads hitting the stop that keeps them from moving off the platters completely. What is happening -- the heads can't tell where the tracks are, so they keep swinging, until they hit the stop. This gets noticed, the controller retracts the heads all the way to the center, and it tries again.

WHACK. WHACK. WHACK.

This means: 1) The heads can't sense position information, and 2) The drive is almost certainly toast. 95% of the time, it's the head that's on the servo platter. 5% of the time, it's a controller or power issue. You can try the drive in another computer, but usually, you ask the $1000 question, which is "Is the data on this drive, that I haven't backed up recently, despite the lectures every sysadmin has given me repeatedly, worth $1000?"

That being the cost of sending the drive off to the clever guys with lots of toys who can read the data off.

IOW. The drive is almost certainly toast. If the data is really important, you can send it to a disk recovery place, who will charge you lots of money, and send back the data on CD or whatnot. If it's not, you buy a new drive (or two and a mirroring controller) and resolve to be better about backups next time.
posted by eriko at 7:32 PM on January 27, 2006 [2 favorites]