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Re: [vox-tech] backing up the master boot record
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Re: [vox-tech] backing up the master boot record

On Tue, 19 Jun 2001, Mister Resistor wrote:

> On Tue, 19 Jun 2001, Peter Jay Salzman wrote:
> > i'd like to know how to backup the master boot record, but the trouble is
> > that i don't know how "big" the mbr is.
> >
> Take all 512 bytes -- it won't hurt.  Disk sectors are usually 512 bytes
> or multiples of 512 bytes.  Lilo may not use the last set of bytes - but
> usually MBR's and bootsectors have 0xAA55 written at the end.  Some
> systems might let you get away with that 446 byte count MBR, but others
> will demand that the 0xAA55 signatures is written to the end of the
> sector.  In any case, just take all 512 bytes.

512 is the right number.

However, you would not want to take more than the correct number of bytes,
because when you re-write the mbr you won't want to restore data that may
have changed in the sector(s) immediately following the mbr.  Nor would
you want to get less than the correct number of bytes, because rewriting
part of it might not restore a completely functional mbr.

Thus, your assertion that "it won't hurt" assumes you have chosen the
right number, and Pete is simply trying to confirm that value.

Jeff Newmiller                        The     .....       .....  Go Live...
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