Re: Cannot boot xp
From: Justin Pryzby <justinpryzby@users.sourceforge.net>
> On Tue, Feb 22, 2005 at 01:51:20PM +0000, Floris Bruynooghe wrote:
> > On Tue, Feb 22, 2005 at 01:28:01PM +0100, xerces8 wrote:
> > > From: "xerces8" <xerces8@butn.net>
> > >
> > > BACKUP the partition table to somewhere where you can access
> > > it if you break the disk layout ! Like on a floppy or network drive.
> > > "sfdisk -d > part_table_backup" is a good backup IMO.
> Good call:)
>
> > "dd if=/dev/hda of=/floppy/mbr.backup bs=512 count=1" looks like a
> > better one to me. Altho that copies the mbr as well which might be
> > undesirable under certain circumstances. IIRC only the last 64 bytes
> > of that file will be the partition talbe but you should really check
> > these things before you do them.
> Close. The MBR is 512 bytes, and includes the partition table. The
> last two bytes are a magic number "0xAA55" (or byte-swapped). The 64
> bytes previous to that are the partition table, with 16 bytes per
> partition. And the other 450 bytes are machine code, usually starting
> with a jmp instruction, possibly with a couple bytes of ASCII (like
> the "L" in LILO).
No, that will miss out the logical partitions. They are stored in the beginning
of their extended partition. And that is obviously not in the first sector
of the disc, that dd would back up. Trust me, "sfdisk -d" is good ;-)
Regards,
David
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