Utterly fascinating boot sector problem: "Differences: (offset:original/backup)"

Bert · 01-03-2003, 04:40 PM

This is not a big problem - it's an irritation, because it slows boot time. More irritating is the fact that I'm not sure how it happened.

I was busy installing Windows 2000 on VFAT (I only use it to test ASP.NET stuff for go-mono.org) although it's better than every other offering of theirs. Aneeway, I get this message now on startup:

Code:

Dec 30 18:44:21 localhost fsck: dosfsck 2.8, 28 Feb 2001, FAT32, LFN
Dec 30 18:44:21 localhost fsck: There are differences between boot sector and its backup.
Dec 30 18:44:21 localhost fsck: Differences: (offset: original/backup)
Dec 30 18:44:21 localhost fsck:   90:33/fa, 91:c9/33, 92:8e/c9, 93:d1/8e, 94:bc/d1
Dec 30 18:44:21 localhost fsck:   , 97:8e/7b, 98:c1/8e, 99:8e/c1, 100:d9/bd
Dec 30 18:44:21 localhost fsck:   , 105:4e/00, 106:02/1e, 107:8a/56, 108:56/16
Dec 30 18:44:21 localhost fsck:   , 111:08/22, 112:cd/05, 113:13/89, 114:73/7e
Dec 30 18:44:21 localhost fsck:   , 117:ff/4e, 118:ff/02, 119:8a/b1, 120:f1/0b

And much, much more. When I first tried to correct this with fsck.vfat it asked me which to copy, backup to original or original to backup. Technically that's a confusing question, as your original is your backup and the new is the err, new, isn't it?

So I can't make this problem go away now because presumably, the original is the same as the backup. (I'm assuming fsck.vfat is talking about the offset of the mbr, but grub is installed there).

Any ideas, anyone?

Thanks
Bert

Bert · 01-04-2003, 06:15 PM

Told you it was fascinating.

*yawn*

There must be someone who knows? Unfortunately there's no fdisk /mbr on Windows 2000, and reinstalling grub won't work.

Ah well.

Bert · 01-05-2003, 12:05 PM

Well, this is how it was fixed.

Windows is not so hot at managing it's boot sector, and Windows 2000 doesn't even have fdisk.

To make sure it was repaired properly I used the Win2000 disk and went into repair mode.

Run fsck.vfat in Linux with the -ar switches to write the repair to the disk.

After that of course, you can re-write the mbr with grub or lilo or whatever.

The moral of the story is: Windows 2000 is really rubbish at managing itself at the partition level.

I know everyone was very anxious to get a solution for that one. Phew!

Bert

willz06jw · 04-30-2007, 06:04 PM

Bert, I know you wrote this over 4 years ago but I had the same problem with 7.04 Ubuntu Feisty. I cleared it up by using

Code:

sudo umount /dev/hda1

and then

Code:

sudo fsck.vfat -ar /dev/hda1

It fixed me right up.

Thanks,
Will

phantom630 · 07-01-2013, 05:29 PM

...and 6 years after the last post; this thread helped me repair my FAT bootsectors after a Windows repair operation in my multiboot computer.

i think this thread is something like a ritual, happening every several years

thanks to the OP!