Is the scan disk and check disk command ( CHKDSK ) is really fixing the hard disk error, or at the very minimum, stops the hard disk error from propagating?
I don't think that they'll fix the errors, but they will find and mark those sectors that are damaged so that when won't be written to in the future. This should stop write errors (at least for a while).
If you are getting these sorts of error it could indicate that the hard drive is failing, so you might be better off investing in a new one and transferring your data.
Scan disk and Checkdisk will not fix the hardware :)
Occasionally the various systems used to ensure the OS knows where files are stored on disk gets corrupted and Scandisk and Chkdsk will help to recover this information. This used to happen quite a bit in the days of DOS, Win 3.1, Windows 95/98 but happens less and less with modern hardware and modern OS's.
It recovers the link to the files if it can but it doesnt necessarily stop it from happening. If it happens on any kind of regular basis change your disk before you lose everything.
I have been trying to mirror my OS disk, but the process keeps stopping with a "Disk I/O" error. Eventually I found a Microsoft Support article that explains why:
The article explains that CHKDSK and Scandisk will not remap bad sectors at a hardware level. They only mark bad sectors at a filesystem level. (The disk mirror process copies the hard disk sector for sector.) Therefore, you need a low-level error-checking utility that will remap bad sectors in the hard drive's own table. You can use SeaTools for DOS to do this. Another, proprietary, solution is SpinRite by Gibson Research.
I disagree with Chris' answer, but your question is also not clear. What kind of "hard disk errors" are you talking about? Bad sectors are somewhat like bad pixels: The manufacturer will allow disks with a certain number of them to pass inspection.
Remapping bad sectors with a low-level tool will stop error propagation, but new damaged sectors could occur if there is a physical problem with the drive.
I am totally agree with my friends
Scan-disk Does not fix hardware error but it is use to fix logical errors of windows (keep in mind not corrupt files or etc)
as far as i know check disk is use to check the status of Hard-disk and lists and corrects errors on the disk.
sometime it is use for file indexing purpose