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 Post subject: recovering lost fat 32 and ntfs volume boot record
 Post Posted: Fri Dec 03, 2010 1:09 pm 
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Joined: Wed Mar 03, 2010 2:54 am
Posts: 29
Location: Italy
Hi Scott and Mike.
Scott, in your book “Upgrading and repairing Windows” 2nd edition, on page 629 you tell about how to recover a FAT32 volume having its VBR get corrupted, by means of replacing its VBR with a backup copy automatically created by FAT 32 file system (if I understood right).
In more detail, you say the default copy of FAT32 VBR was located at sectors number 63, 64 and 65 and the backup copy was located at sectors number 66, 67 and 68, i.e. it starts just after the end of the default copy.
But on pages 634 and 648 through 650 you state (if I understood right) that the default copy of FAT32 VBR is at sectors number 0, 1 and 2 of the volume and the backup one at sectors 6,7 and 8, i.e. the backup copy starts three sectors forward from the end of the default copy.
Also on page 636 you state that backup of third sector of FAT32 VBR is at LBA 8.
I would like to ask you how to coordinate these two statement, which seem to me to be in contrast each other.
Perhaps it is due to some misunderstanding by me but I cannot catch their right meaning.
More in general I would like to ask you how I can recover an NTFS formatted disk VBR. And at which sector address can I find it?
Is there a book in which I can find answers to these questions?
I've searched Amazon some time ago, but found only a book (by you) about data recovery dated back in 1991 (too old, I think).
Thank you very much in advance.
Massimo
Maxz222


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 Post subject: Re: recovering lost fat 32 and ntfs volume boot record
 Post Posted: Fri Dec 03, 2010 2:54 pm 
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Quote:
...you say the default copy of FAT32 VBR was located at sectors number 63, 64 and 65 and the backup copy was located at sectors number 66, 67 and 68, i.e. it starts just after the end of the default copy.

Whoops, it seems I've made an error. The backup was really at LBAs *69 through 71*. This means that the passage in the book on p. 629, 2nd paragraph that reads:

    I knew from experience that FAT32 keeps a backup copy of the three-sector-long VBR at LBAs 66 through 68. So I used Disk Probe to copy sector 66 and paste it over sector 63, thereby restoring sector 63 and instantly solving the problem.

Should read like this instead:

    I knew from experience that FAT32 keeps a backup copy of the three-sector-long VBR at LBAs 69 through 71. So I used Disk Probe to copy sector 69 and paste it over sector 63, thereby restoring sector 63 and instantly solving the problem.

In other words, in this example the primary VBR was at LBAs 63 through 65 (sectors 0 through 2 in the volume), and the backup was at LBAs 69 through 71 (sectors 6 through 8).

Quote:
But on pages 634 and 648 through 650 you state (if I understood right) that the default copy of FAT32 VBR is at sectors number 0, 1 and 2 of the volume and the backup one at sectors 6,7 and 8, i.e. the backup copy starts three sectors forward from the end of the default copy.

That is entirely correct.

Quote:
Also on page 636 you state that backup of third sector of FAT32 VBR is at LBA 8.

I'd call that another error (ouch!), since it should read "sector 8" instead of "LBA 8". Under standard partitioning and formatting rules, relative sector 8 (the 9th sector in the partition) in the first volume would be at physical sector (LBA) 71, since the first volume normally starts at LBA 63.

Obviously it can be confusing when talking about LBAs (sector addresses that start at the beginning of the disk) vs. relative sectors (sector addresses that start at the beginning of the volume). This is especially true for volumes other than the first one, which can start just about anywhere on the disk.

In any case I'll correct those statements in the next edition, thanks for pointing them out!

Quote:
More in general I would like to ask you how I can recover an NTFS formatted disk VBR.

One way to do that would be to use a disk editor to copy the sectors containing the backup VBR over the sectors containing the (corrupt?) primary one.

Quote:
And at which sector address can I find it?

You'll find that information in the last paragraph on p. 636, where it states:

    The VBR on NTFS volumes is 7 sectors long, although 16 sectors are reserved at the beginning of the disk for the VBR. A backup of the 16 sector VBR area is reserved at the end of the volume, which contains a backup VBR.

The specific sectors involved will obviously depend on where exactly the volume in question ends, which also depends on where it starts and how long it is.

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Is there a book in which I can find answers to these questions?

Yes. <g> Scott.


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 Post subject: Re: recovering lost fat 32 and ntfs volume boot record
 Post Posted: Sat Dec 04, 2010 6:20 pm 
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Joined: Thu Jan 15, 2009 1:27 pm
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Location: Stowmarket, Suffolk England
Vaguely related

http://www.bleepingcomputer.com/forums/topic364894.html


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 Post subject: Re: recovering lost fat 32 and ntfs volume boot record
 Post Posted: Mon Dec 06, 2010 12:31 pm 
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Joined: Wed Mar 03, 2010 2:54 am
Posts: 29
Location: Italy
Scott, thank you very much for your very clear and complete answer.

Quote:
Quote:
And at which sector address can I find it?

You'll find that information in the last paragraph on p. 636, where it states:

The VBR on NTFS volumes is 7 sectors long, although 16 sectors are reserved at the beginning of the disk for the VBR. A backup of the 16 sector VBR area is reserved at the end of the volume, which contains a backup VBR.


The specific sectors involved will obviously depend on where exactly the volume in question ends, which also depends on where it starts and how long it is.

I apologize for not having enterely read the book paying the attention I should to.

Bye.
Massimo
maxz222


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