A computer's hard drive is both its most fragile and its most important component. Drive reliability has improved together with storage density, but a computer's hard drive is still the most likely component to fail. In most computers, all "permanent" data is stored on its hard drive, so when it fails, you've lost all of its data.

I've installed, replaced, and rehabilitated thousands of hard drives and don't recall any particular name brands as "bad". Occasionally, one model may prove to have problems, but I think that the competition in the hard drive arena is so fierce that it pushes inferior products out. Usually by the time a particular model proves to be troublesome it's obsolete and out of production anyway.

Interior of hard drive


Desktop: Approximately 3.5 inch platter diameter
Laptop: Approximately 2.5 inch inch platter diameter

Detailed description

Drive interfaces

IDE/ATA (Integrated Drive Electronics): suitable for desktops and laptops
SATA (Serial ATA):Will supersede IDE; for use in laptops and desktops
SCSI (Small ComputerSystem Interface): servers and high-end workstations
FC (Fiber Channel): servers

Hard Drive Crash?

All you Need to Know About ‘Hard Disk Crash’

Crashed Drive Data Recovery

Hard drive schematic
Hard drive schematic 2
drawings: Surachit
Major components in a hard drive, excluding the printed circuit board. The platter spins at 4200, 5400, 7200, 10,000, or 15,000 rpm.
Six hard disk drives with cases opened showing platters and heads
Six hard disk drives with cases opened showing platters and heads; 8, 5.25, 3.5, 2.5, 1.8 and 1 inch disk diameters are represented.
photo: Paul R. Potts
Disassembly of a Hard Drive (should be done in a clean room)
photos by: Alessio Sbarbaro