Re: Bootloader produces garbage - reconstructing MBR

From: Alvin Oga (aoga_at_mail.Linux-Consulting.com)
Date: 07/04/05

  • Next message: Rick Pasotto: "sarge and sound" 
    Date: Sun, 3 Jul 2005 19:53:13 -0700 (PDT)
To: Haines Brown <brownh@hartford-hwp.com>

    On Sun, 3 Jul 2005, Haines Brown wrote:

    > It happened that I could no longer mount my ide cdrom or my scsi cdrom
    > drives

    that is a simple kernel option problem
            - fix lilo/grub config files
            - manually installt he modules manuall

    > I can boot all three disks from a grub boot floppy, which I assume
    > narrows things down to what's in the sda MBR rather than a hardware
    > problem.

    good.. says grub's MBR on the floppy is correct
     
    > I copied (dd) the MBR on sda and sdc to img files. Being binary files,

    how exactly was the dd command ??

            dd if=/dev/fd0 of=/dev/sda bs=448 count=1

            any other "dd" command is WRONG

            - NEVER copy binary files from xx to yy versions

    > I could not get diff to tell me anything more than that they differed,

    duh... why should it be the same

    -- use the latest grub via cvs from gnu.org

    > I need to do a MBR check, repair or restoration.
    ..
    > To wipe the MBR clean, I read of doing # fdisk /MBR.

    wipe it ( fdisk /mbr or dd if=/dev/null of=/dev/sda bs=448 count=1 )
    and rerun lilo or grub

    > Other than making the disk
    > unbootable from its bootloader, which is already the case, are there
    > any particular dangers doing this?

    you dont need to worry.. you ahve a working boot floppy...
            save it as it.. forever

    > I assume simply means doing >grub root and >grub setup.

    grub-install /dev/sda
    or
    grub-install /des/db
    ...

    c ya
    alvin 

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