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Boot Sector Curruption


Harut

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what can cause boot sector curruption? MBR curruption?

my laptop refused to boot yesterday. good thing was that i was able to fix it. but now i want to know what precautions to take to avoid it later.

 

(Azat, Seapan, vava!!! please don't shout "back up!!!")

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There are usually 2 copies of the MBR I think anyway ... usually an FDISk /MBR command fixes that problem although I haven't had that happen in YEARS. What can cause it? Hmmmm ... tough question ... a failed attempt at OS upgrade/install? Some partition utility like partition magic? Boot loaders like LILO etc ... dual boot managers ... anything that would try to write to the boot sector.

 

Other causes can be disk failures and crashes and there are boot-sector virsuses out there although nothing recent that I know of. I don't think getting that kind of access to the disk is too easy under the new windows OSes but I don't really know.

 

Oh, and dont' forget BACKUPS!

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... FORMAT.COM writes two copies of the MSWIN4.1 Boot Record (for FAT32 partitions) to the drive. The first occupies Absolute Sectors 63 through 65 and the second Sectors 69 through 71; Sectors 66 through 68, plus all of the sectors through Absolute Sector 94, are filled with zero-bytes! ...

 

... from this site. So that's probably what I was thinking about ... two copies of the windows boot record on Fat32.

 

I also found this nice site that has good explanations on what is where on Fat-16 and the location two copies of the FAT for anyone that didn't know the details like me.

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... from this site. So that's probably what I was thinking about ... two copies of the windows boot record on Fat32.

 

I also found this nice site that has good explanations on what is where on Fat-16 and the location two copies of the FAT for anyone that didn't know the details like me.

Yes it seems that version of format does keep a copy of MBR on logical sectors 6-8.

While a lot of programs use the 2nd copy of FAT table for verification and to restore damaged copy of main FAT table I haven't came across any notes about restoring MBR from that 2nd copy. fdisk itself contains a copy of MBR in it and having a copy on the hard disk makes sense only if it refreshes the 2nd copy every time you make a disk configuration change.

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thanks for the answers people.

 

Garo

yes, i have installed software recently, but unfortunately too many of them. so, now can't say exactly which one would cause it.

but i have a strange suspicion that it had something to do with putting the computer "asleep" and "waking up". i don't turn on/off the laptop too much, but just keep suspending it and putting it back on.

and whatever happened, happened right at the time of "waking up".

the HD started making funny noises, the unlock prompt didn't show up. so i restarted it. and.... never started it again. (good thing i could fix it)

that kind of thing (getting crushed at the "waking up") had happened once before, but rebooted pretty successfully.

so, i don't know.

 

Mos jan, im laptop@ 17 voltov a.

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This happened to me a LONG time ago - and I had just installed a second OS (dual boot) - it was a desktop so no suspend/wake up issues. Some restore utilities like Norton, allow you to make rescue disks and keep a copy of the Boot record for this purpose. They'll also prompt you when it has been modified, if you need to make new rescue disks. I suspect (although I'm really not sure) that the advances in hard disks/storage devices has probably helped to reduce the incidences of boot record damage... :huh:
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