What to do when a drive shows some flakiness

A friend asked what I do when a drive throws a sector error. Do I junk the drive?

The answer is "no", but I do torture it. I did a lighter version of this recently when I started hearing suspicious "whirrrrrrr - tick" sounds from a laptop drive (seek error sounds). Here's the full OS X regimen; the XP response is pretty similar (scandisk instead of Disk Utility, etc).

1. Do a mirror backup (Carbon Copy Cloner, etc) and a Retrospect backup (that's what I use routinely).
2. Test with Disk Utility.
3. Run Apple's drive diagnostic in loop mode (hardware test).
4. Reformat using a secure format (write 0s, so it write tests every sector).
5. Test with Disk Utility.
6. Restore from mirror backup.
7. Test with Disk Utility.
   

If you start in the morning you can probably get it done within a day. Replacing the drive takes longer than a day, so even if a replacement were free this is worth doing. If the drive passes step 2 it will likely pass all the tests, so the chance of wasting a lot of time is pretty low.

See also (XP centric): Gordon's Tech: Lessons from another XP disk crash