fixmbr

[david90]

I know that fixmbr is suppose to help fix the master boot record but how exactly does it do it? I can't find resources that describe exactly how fixmbr recovers and rewrites the mbr.

I purposely corrupted a PC's mbr and tried to use fixmbr to fix it but I didn't see any changes to the mbr. The mbr was still corrupted after using fixmbr.

 

[eyeCpc]

The Master Boot Record (MBR) and Why it is Necessary? What occurs during the System Boot Sequence? The detailed explainations for those and other information on the "master boot record" is seen at http://www.dewassoc.com/kbase/hard_drives/master_boot_record.htm

As it explains there "The master boot record is always located at cylinder 0, head 0, and sector 1, the first sector on the disk.".

A lot now for seeing that corrected will depend on just what you did to what type of drive by what method when you say you intentionally corrupted the mbr. Hopefully you didn't the drive beyond repair.

 

[berry120]

It fixes it by rewriting it, it's a part on the disk that gets written over when you run fixmbr. It doesn't recover anything - just rewrites it with a default value.

What did you do to corrupt it though? Are you sure you didn't corrupt the drive's firmware or something similar as well (which is nigh impossible to get back on there after you've taken it off or corrupted it?)

 

[david90]

i corrupted the mbr signature "AA55h" and the partition table. fixmbr wasn't able to fix it.

I actually made it worse.

I'm tyring to find out how fixmbr works so that I know when to use it and when not to use it.

 

[eyeCpc]

First you have to recover the partition table before you can do anything. Hopefully you didn't trash the partition entirely otherwise you be forced to repartition the drive there.

For that you'll probably have to use a program like DiskInternals Partition Recovery or another similar program either downloading the shareware or trying out different freewares. http://www.diskinternals.com/partition-recovery/

You can't see new entries written for a partition that's toast if the PT is unable to be repaired. But be prepared to except the fact that even a good program may not be able to salvage the present set you have on the drive.