A system with a failing hard drive (HDD) may exhibit the following symptoms: 

• Blue Screen of Death (BSOD) crashes.
• Does not boot to Microsoft^® Windows^®.
• During the BIOS POST process after reset or switch on, you may see an 'Insert system disk' or similar error message.
• Files or partitions appear corrupted.
• PC runs very slowly or freezes occasionally.

Although hard drives are much more robust than people give them credit for, they can fail due to their mechanical nature (spinning disk and moving heads). The read/write heads of a modern hard drive hover extremely close to the disk surface in order to allow high capacities. Vibration and temperature in particular, can result in 'head crashes' which cause surface damage to the disk. Data written on the disks can therefore easily become unreadable in places.

The HDD will attempt to copy affected data to other parts of the disk (reallocated sectors) but there are limited spare sectors and sometimes data is completely unreadable. Other forms of damage are in the HDD motors which spin up the drive. If there is mechanical wear/tear/fault, the drive logs the number of retries to successfully spin the drive up to full speed.

All these attributes are logged and viewable via a SMART log on the drive itself. It helps diagnose and keep track of the drive's health and provides useful information in determining if a PC fault lies with the HDD or somewhere else.

Download and install HDDScan.exe from: http://hddguru.com/ (version 2.8 or later)

1. Log on to the system with Administrator access.
2. Run HDDScan.exe.
3. Select the desired source disk for a multiple hard disk setup. In a single hard disk setup leave the source disk as drive 0.
4. Press the SMART button. A dialog box will appear with the drive's SMART data contained on it. 
   Note: A log file called smart.txt will be written to the same folder as HDDScan.exe was saved to.
5. The SMART attributes are labelled RED, AMBER or GREEN status.
6. Please refer to the results window or log file and details below to help confirm the diagnosis.

Download and install the freeware propgram smartudm.exe from: http://www.sysinfolab.com/download.htm

1. Create an MS-DOS bootable floppy disk or bootable USB pen drive and copy smartudm.exe onto the media.
2. Boot to MS-DOS and run smartudm.exe.
3. Follow the screen prompts to save the SMART log.
4. Please refer to the results window or log file and details below to help confirm the diagnosis.

Some attributes are critical to the health of the hard drive. Critical attributes (in red) refer to potential of electro-mechanical failure or increasing errors on the hard drive in the short term, leading to eventual drive failure. If any critical attribute is showing as amber status in HDDScan, this is a good indicator that the HDD is an issue. If a non-critical attribute is amber (such as temperature) then this is worth keeping an eye on but is not an HDD issue. However, any red attributes are indicators of significant HDD issues. Green attributes indicate a healthy drive. (The Smartudm output screen shows an indicator for the attribute status. The number of green 'blocks' will decrease towards the red block showing how bad an attribute is.)

Note: Different drive manufacturers use different SMART attributes and several of the following may be missing from the output logs.

A SMART attribute is anything that the hard drive manufacturer thinks is worth checking and that might be a useful indicator of the health of the hard drive.

The raw values in hex are converted into a value. This value is weighted as a score out of 100 or out of 200 or whatever the drive manufacturer chooses to represent the condition of the hard disk.

Value is the current reading for that attribute. Worst gives you the worst value that the hard disk has recorded for that attribute. Threshold value gives you the minimum allowed before a failure will be recorded.

Not all failures necessarily indicate a hard drive failure. Some attributes are not critical and some can correct themselves over a short period of time.

For further HDD testing, the manufacturer specific tests are available from the links below.

To identify which make of hard drive you have in your PC, please refer to the RM Equipment log. To find this log, follow TEC104348 in the Other Useful Articles section below.

Hitachi Drive Fitness Test for MS-DOS or Windows:
www.hitachigst.com/hdd/support/download.htm

Western Digital (WD) Data Lifeguard Tools for MS-DOS or Windows:
http://support.wdc.com/download/indexns.asp#diagutils

Maxtor/Seagate SeaTools for MS-DOS and Windows
http://www.seagate.com/www/en-us/support/downloads/seatools/