Many computer users worry when they see "bad sector" error messages, and sector issues are certainly a cause for concern. However, before you take any actions, you need to understand exactly what bad sectors are and how they affect the overall health of your hard drive.
Bad sectors are unreadable sections of your disk. Sectors can become unreadable for a number of reasons including platter damage and actuator head offsets. Regardless of what causes the issue, the end result is the same: a very small portion of the hard drive is permanently damaged and completely unusable. Bad sectors are typically un-fixable, and they tend to multiply over time.
Sector Issues and Disk Utilities
Computer users usually notice bad sectors when running programs like CHKDSK and ScanDisk. These disk utilities scan the surface of your hard drive, identifying unreadable areas and performing basic processes to avoid these areas, which improves read/write speeds.
After running a disk utility, you will receive a report that shows the number of bad sectors on the drive. You may see a warning message if there are a fairly large number of bad sectors, but in most cases you will see a simple list with your drive's total space, available space, and the size and location of any bad areas.
Your disk utilities will not list every unreadable sector on your disk. Because hard drives are relatively dense, perfect storage is nearly impossible, and drives ship with a limited number of bad sectors. The drive's firmware stores a list of these bad areas, and your disk utility will skip past these sectors when operating.
Is One Bad Sector a Cause for Concern?
Many online resources suggest that you should replace a hard drive when a disk utility reports a single bad sector. In our view, this is unnecessary. Most drives develop some bad areas over time, and several damaged sectors are not a cause for concern on an older drive.
However, if you run disk utilities regularly and notice bad sector counts increasing dramatically, the drive will probably fail. You cannot safely store data on the device, as files with bad sectors will show up as corrupt or unreadable.
Many computer users ask our engineers whether there is a golden rule for sector issues. Depending on the size of your hard drive, a relatively small group of bad sectors could seriously affect the dependability of your disk, but the bottom line is that there is no set number of bad sectors that qualified a hard drive as broken or physically damaged.
However, if your drive starts suddenly accumulating bad sectors during disk utility checks, you should immediately back up important data and replace the device. Do not attempt to use software to fix your drive. Do not run additional disk utilities, as programs like CHKDSK can contribute to file corruption when used incorrectly.
The good news is that data corruption is fairly treatable in most instances. Data recovery engineers will need to treat physical hard drive issues before making a copy of your drive and reconstructing your files with software utilities. You can improve your chances of recovery by turning your drive off right away and keeping it powered off until you can find a qualified hard drive recovery provider.
Of course, the easiest way to avoid data loss is to keep your files backed up. Monitor your hard drive's health regularly and run disk utilities once or twice per week. If you notice drive damage, replace your hard disk right away to keep your computer running smoothly.