There mainly two reasons for scanning a computer hard disk: one is to examine it for filesystem inconsistencies or errors that can result from persistent system crashes, improper closure of critical system software and more significantly by destructive programs (such as malware, viruses etc).

And another is to analyze its physical condition, where we can check a hard disk for bad sectorsresulting from physical damage on the disk surface or failed memory transistor.

Read more at Tecmint

Click Here!