Editing the partiton table 2

[Guest_imported]

My C drive(bootable FAT32 ) is stuffed. The MBR and boot records are corrupted so i can't read it or access it.

I had a look at the partition info using a Powerquest boot disk. Out of the four rows The hex info starts at row 3, where as on my other hdd(healthy working drive) it starts at row 1. Does this mean a problem? is the problem fixable or is it yellow pages time?

 

[edfair]

Since both are corrupted I would suspect that the build is now trashed. Ed Fair
unixstuff@juno.com
Any advice I give is my best judgement based on my interpretation of the facts you supply. Help increase my knowledge by providing some feedback, good or bad, on any advice I have given.

 

[Guest_imported]

I'm hoping dinosnake would answer the question he seems to be the most knowledgeable on this sort of area.

Anyone know his email address?

 

[rwise2112]

What operating system? If you are using Windows XP, you can boot to the Recovery Console using the OS CD, and run the FIXBOOT and FIXMBR commands.

If you're using 95/98/Me the FDISK /MBR command will rewite the MBR which might help.

 

[wolluf]

This page

http://www.datarescue.com/laboratory/partition.htm

might be useful if rwise's suggestions do no good - but if they don't your MBR is probably shot. You don't say how you wrecked it - but having a tool which will save & restore MBRs (or track 0) is a good idea if you experiment in that area. There's one at

http://www.boot-us.com

(a good boot manager site).

 

[dinosnake]

Thank you for the request!

With the right (2) tools, believe it or not, this is *incredibly* easy. And modestly automatic, too.

Now, you didn't mention which OS created and formatted the partition, but this has works on various systems I've tried.

The two tools you need is Norton DiskEdit and Norton DiskDoctor32 (diskedit.exe and ndd32.exe).

The technique is simply and sneaky.

(1) Run DiskEdit in MS-DOS mode only
(a) In 'Tools' / 'Configuration' make sure DiskEdit is out of 'Read Only' mode
(b) In Object / Drive make sure C: is selected (use your scroll keys if necessary), then hit <Tab>, then hit the <Spacebar>, then hit <Enter>. This will select the C: drive for direct, physical access.
(c) You should be at Cylinder 0, Side 0, Sector 1 of the hard disk (look at top, directly under menu bar for location readout). If not, try again.
(d)In 'Edit', select 'Mark'.
(e) Use your <Page Down> key to scroll down about 15 sectors. A black area will highlight all areas above your current selection.
(f) In 'Edit', select 'Fill'
(g) Select select '00', hit <Enter>. Confirm any warnings with <Enter>.

(2) Run DiskDoctor on the drive. Confirm searches - rerun DiskDoctor if the program asks you to reboot before it can continue.

What did you do?? By removing the MBR completely you FORCE DiskDoctor to COMPLETELY rebuild the MBR and search for partitions across the entire drive. Without doing this it won't go through all the steps as it feels no need.

Nothing like forcing the issue, yes?

If you really want to look at the details of DOS compatible drives I would recommend:

http://home.teleport.com/~brainy/fat32.htm

As you can see the structure is complicated, and not quite fully hand rebuildable as you would have to write the bootstrap entries, plus all correct MBR info along with correct partition references. Now, DiskEdit makes it possible and much less painless than working completely in hex (it will show the MBR in a MBR table (see 'View'), but for the purpose here - why bother?? Force DiskDoctor to do it!

I have an old, old saying regarding computers (at least 15 years):

If at first you don't succeed - push, push harder! Your mileage may vary...

 

[dinosnake]

Oh

If you need the programs I'll supply them. Shhh, I didn't just say that. Your mileage may vary...

 

[Guest_imported]

Initially i couldn't read the boot record for c with a Norton AV scan. Also i had lost CD-ROM support. So i figured a virus. I tried sys c, fdisk /mbr. But Norton asked me to repair when i booted. So i clicked repair and thats where the big problem started. I lost access to c: and i can't access windows 2000 on the D getting ntldr missing. I formatted my norton rescue disks as well heaps ago (what a mistake) But i can access 2000 with a floppy containing NT files. Win ME is in the first partiton. Windows Professional in the second. Created the latter with partition magic.

 

[dinosnake]

And, regretfully, therein lies the problem.

NTLDR and the fact that you use Partition Magic to create the second partition out of the first means that the boot sectors were custom to the individual unit. When you FDISK /MBR'd you commanded MS-DOS to write an _MS-DOS_ boot sector. You didn't have one to begin with, so wham, bam, boom! No access.

FDISK will not be able to create a valid boot sector on the disk because of the Partition Magic intervention in the original structure of the hard drive. When ME was originally installed DOS created the boot, partition, root directory, dual FAT and bootstrap entries. Partition Magic modified the entries (especially the FAT size) away from DOS standard, and now DOS & FDISK cannot handle the 'patched' disk created by using FDISK /MBR. Norton DiskEdit will not help here either, unless you can *exactly* recreate _all_ data values for both partitions, including their hacked FAT start / end entries and other details.

It may be possible to use a boot loader, like NTLDR, to repair this. You'll install *just* the boot loader and _hopefully_ it will be able to handle, and then find, the DOS partition with ME on it. Since NTLDR already accesses 2000 on the second partition you are halfway there - it properly works with that structure as it stands. That's nothing to sneeze at. I found a tech article which will help:

http://www.windowsitlibrary.com/Content/329/25/6.html

Essentially you will boot with the NT Setup disks, #1, #2 & #3, and when at the Welcome screen hit 'R' for repair. Go from there; just select _only_ the Inspect Boot Sector option, which (it says) will repair the boot sector. This, I _think_, should work.

Other than that your only hope is Partition Magic, I believe the Boot Magic program. Partition Magic worked on and created the hard disk structure before, and (seems) to have a function to repair the structure back to a working order. Trying to do the math (for _all_ the entries required for this to work) would probably be just short of humanly impossible.

You will have to reread the instructions - others claim that there are details on how to recreate the boot sector (possibly using the rescue disks (did you create Partition Magic rescue disks??) - or contact PowerQuest for tech support.

I'm sorry that I cannot offer more help. I personally haven't used Partition Magic - and, more importantly, haven't gotten my hands on a drive worked on by Partition Magic to view (in hex) the altered structures. I understand that their messy, though. They work - but what a mess.

If you _do_ get this working you may (please) consider backing up the entire drive - all partitions and data - and then recreate the drive structure using only FDISK. In this manner the partition & boot structures will be OS industry standard. If you do this just make sure you back up the BOOT.INI file for 2000 otherwise it won't work!! (Search the web for info).

If you don't want to do that after getting this all fixed at least make emergency & repair disks for both partitions and the boot sector. Every computer is different - and yours is _really_ different.

Wishing all the best,
Snake

Your mileage may vary...

 

[dinosnake]

I haven't heard from you in a few days - did you manage to get the system working?? Please let me know - I'm interested. Your mileage may vary...

 

[pintail]

I have had a similar problem and would take up the offer from Dinosnake if he would be so kind as to offer!.

 

[dinosnake]

pintail:
I am not sure how long I can continue this thread - I just broke my wrist in a motorcycle accident. So bear with short answers.

What's the prob? What's the system config and with what probs? I'll help if I can.
Your mileage may vary...