3: Hard disk issues

Traditional hard drives are mechanical devices that eventually wear out. There are many signs of imminent failure before a hard disk finally gives up. Some of these signs include:
Slow access times on the affected drive.
An increasing number of bad sectors when running scandisk and chkdsk.
Unexplained Blue Screens.
Intermittent boot failures.
An “Imminent Hard Disk Failure” warning.

Detecting a failing hard disk can be tricky because the early signs are subtle. Experienced computer professionals can often hear a change in the normal disk spin. After the disk deteriorates further, you’ll see the system slow to a crawl. Write processes will take a long time as the system tries to find good blocks to write to. (This will occur if you’re using a robust file system such as NTFS; other file systems will likely Blue Screen the computer.)

When you notice the system slowing down, run scandisk or chkdsk, depending on your operating system. If you notice a bad sector where a good sector existed earlier, that’s a clue that the disk is going bad. Back up the data on the disk and prepare for it to fail soon. Make sure you have a spare disk ready so you can replace it when it fails or replace the disk as soon as you notice the early signs of failure.

Disk noise and scandisk/chkdsk are your best indicators for identifying a failing drive that’s leading to a system slowdown. However, if you are managing a system remotely, or you can’t take the system down for a full chkdsk/R, you can use tools that monitor disk health, such as Executive Software’s DiskAlert.

You may also get a warning message from SMART hard drives that failure is imminent. Sometimes, you’ll get these warnings when the hard drive is fine, due to problems with the hard drive device driver, the chipset driver, or the way the BIOS interfaces with the drive. Check for newer versions of the drivers and BIOS firmware.

Even if it’s operating properly, your hard disk may be a bottleneck that’s slowing down the rest of your system. See the next item for more information on what you can do about that.