(E-Mail Removed) wrote:
> I may have a problem.
>
> I have two hard drives:
> C drive - boot drive - XP SP3.
> D drive - data drive - NTFS - contains only a backup image of C
> drive.
> Partition Manager shows the second drive (D) is 'bad'.
> However I can look at drive D and its backup image using Windows
> Explorer, and all seems fine.
> I would like to fix the error.
>
> I think the problem is a bad MBR on D drive. How can I easily fix
> that? I don't have recovery console installed.
>
> Thanks
>
> Fred
Do you really really need that information on D: ?
Or is your question a more theoretical one ("what if I needed to recover
the data") ?
When you clone a drive (like copy first disk C: and MBR to second disk
to make a backup), you should not boot from D:, until C: is disconnected.
D: won't work right if you do. D: needs to boot once, by itself, and
then it can be booted any time you want, with any mix of disks you want.
But D: should not be able to see C:, when the D: drive is booting for
the first time after the clone. I unplug the C: cable, before
booting the D: exact copy for its first time.
You can use a copy of TestDisk, to "recompute" the MBR. But the tool
requires the human operator, to have prior knowledge of what the
right answer is. For example, if you know there is only one
valid partition on the second drive, and TestDisk finds three
partitions, you know the scan attempt is picking up ancient info
that you'd prefer it didn't find. For TestDisk to work well,
it's up to the user to use "good hygiene" practices, like
really erasing things you wouldn't want TestDisk to find later.
http://www.cgsecurity.org/wiki/TestDisk_Step_By_Step
The Windows utility "chkdsk", is a repair-in-place utility. If
the information on D: is extremely corrupted, chkdsk can make
things worse. The time to use chkdsk, is when you've tested
and convinced yourself the drive is healthy, such that if
chkdsk does some writes to repair things, it doesn't make things
worse. If the disk light is staying on, you're getting "SMART
warnings", or you're hearing "click-clunk" noises, that
is not the time to use CHKDSK. If you do, you could well
kiss the data goodbye. If the drive is sick, and you really
really need the data, the very first thing you do, is a
sector-by-sector copy to a known-good disk. That's your
insurance policy, for when the sick disk fails completely.
If you boot the WinXP installer CD, and use the recovery
console, the utilities "fixboot" and "fixmbr" are on there.
"fixmbr" doesn't do what you think it does. It puts back
the 440 bytes of boot code that is housed in the MBR.
That allows the OS to boot, if you somehow wiped out
the boot code (say, by installing Linux).
The MBR sector also contains four 16 byte primary partition
entries. You can look at the contents of those, using
PTEDIT32, free for download from Symantec.
The MBR also has a signature byte, AA55 up near the end.
But that's not the whole health story. If the D: partition
is NTFS, and there is some damage to the D: file structures,
then "chkdsk" from within Windows or from the recovery console,
can fix trivial problems. If the damage is bad enough,
you may need a file scavenger to get some percentage of
the whole thing.
Paul
