Crash and Burn | Hard Drive Maintenance

Jan 1, 2009 12:00 PM, By Steve Oppenheimer

WHY HARD DRIVES FAIL AND WHAT TO DO ABOUT IT

BONUS MATERIAL
More on Care and Feeding for Your Hard Drive

Motor failure

If the drive motor fails, your drive either will spin at a degraded and unpredictable speed or won't spin at all. You can't prevent this, but you might hear the motor speed waver in time to be able to power down and try to minimize damage.

Other damaged components

A broken read/write arm, scratched platters, and bad drive bearings are deadly. All sorts of things can cause them to occur: impact damage, a head crash, heat, dust inside the case, a defective part, and so on. Baby your drives — don't bounce them around, pad them well if you transport them, and don't drop them.

Water or fire damage

These are obvious drive killers. Enough said.

Logic Failure

Hard drives can also fail because of logic problems, including the following:

Bad drive sectors

Bad sectors are less of a problem with modern drives than with older ones, but when they appear, you should be concerned. If the number of bad sectors has increased even slightly since the previous time you checked, it's time to replace the drive.

Disk fragmentation

When you save or modify a file, the operating system looks for sufficient free disk space to store the data. The same thing happens when the OS and applications overwrite old files and write new ones (this includes temporary files and updaters). If the OS can't find enough contiguous space, it has to break the file into pieces — fragments — that can fit in the available free blocks of space. Over time, pieces of files and applications are increasingly scattered across the disk; this is called fragmentation (see Fig. 2).

When you delete a file, it isn't erased; it is deleted from the directory, allowing the computer to gradually overwrite those blocks. This can create fragments. And because large audio and video files require big blocks of free space, they become fragmented far more quickly than smaller files.

The directory, stored on the disk, keeps track of the fragments. When the computer opens a file, the directory tells the drive to find and reassemble the parts into a coherent file. This happens on the fly, constantly, at very high speed. The more fragmented a hard disk becomes, the harder the drive has to work to find the scattered pieces. This creates heat and stresses fragile, precision parts. Eventually it can cause the drive to fail. Therefore, defragmenting is an important aspect of drive maintenance.

True disk optimization is different from defragmentation. Optimization organizes related files and files that are commonly accessed together into logical groups for faster access. For instance, applications will launch faster if the files they require are located together, so the drive doesn't have to work hard to find them. Here I'm talking about organizing the files on the platters, not within folders or directories on your desktop. All of this takes place behind the scenes. (For information on defragmenting and optimizing software, see the online bonus material “Shattered!”)

Computer viruses

Viruses can wreak havoc on a drive.

Corrupt firmware or bad RAM

Even firmware can get screwed up over time. The RAM cache is usually SDRAM, and like any memory, it can be damaged. You can't do much to prevent this problem from happening.

Warning Signs

If you see any of the following signs of imminent drive failure, stop using the drive immediately:

Your computer takes a long time to boot or hangs completely

Slow boots can be caused by factors other than drive problems, such as a corrupt operating system or having your OS launch a lot of programs at startup. A somewhat sluggish boot disk might just need to be defragmented. But a very long boot time or a failure to boot generally indicates that a drive is encountering read/write failures. Minimizing the number of programs that automatically launch at startup will enable you to more easily notice slow boot times.