Re: restoring MBR

[Camaleón <noelamac@gmail.com>]

On Sun, 31 Jul 2011 16:50:35 -0400, Stephen Powell wrote:

> On Sun, 31 Jul 2011 11:30:38 -0400 (EDT), Camaleón wrote:
>> ...
>> But regardless the option the user select at install time (do not
>> install any bootloader, install it in a partition or another place or
>> just putting it into MBR), it would be nice the installer makes a copy
>> of the original MBR and leaves it under "/boot".
> 
> Sometimes restoring a backup copy of the master boot record can be even
> more dangerous than wiping it out.  The master boot record contains the
> master boot record boot program, but it also contains the partition
> table.  If any partition changes were made during installation
> (partitions were created, deleted, moved, resized, etc.) then simply
> replacing the master boot record with an older copy will not only
> restore the old master boot record boot program but will also restore
> the old partition table.  This can lead to permanent data loss.  One
> must be very careful about how one goes about restoration in such cases.
>  In most cases, one doesn't want to restore the entire 512-byte sector,
> but only a portion of it: up to, but not including, the partition table.

If you add encryption to the equation things can be even worst.

While I agree that "playing" (backing and restoring) with MBR can be 
dangerous I also think that having no previous copy is equally bad. I'm 
not aware of any data loss for just making a backup of the MBR at install 
time. Restoring is another thing but if you have a copy of the original 
MBR at least you have something to test (or to compare) with.

Greetings,

-- 
Camaleón