Re: Two GRUB setup can boot one each of two installs, but not the other, why?

[Michael Evans]

On Thu, Dec 17, 2009 at 5:27 AM,  <address@hidden> wrote:
>
> Hi,
>
> I have a very strange GRUB problem, that got me totally stumped.
>
> My system has two disk drives, one of which with two Linux installs.
> MBR of each disk has been setup from one of the two Linux installs,
> and both to allow booting either Linux:
>
> IDE disk (MBR setup from IDE part2 (Ubuntu 8.04))
> Part1: Mint 7 (Ubuntu 9.04 based)
> Part2: Ubuntu 8.04
>
> SATA disk (MBR setup from IDE part1 (Mint 7))
> Part1-5: swap and user-data partitions
>
> Grub version of both Linux installs is 0.97.
>
> I have following pair of stanzas for both of Linux installs in their 
> respective
> /boot/grub/menu.lst:
>
> title           Linux Mint 7 Gloria KDE, kernel 2.6.28-11-generic
> #root           (hd1,0)
> uuid            3403d691-06fd-4646-840c-8f936fd99ab9
> #kernel         /boot/vmlinuz-2.6.28-11-generic root=/dev/sdb1 ro quiet
> splash
> kernel          /boot/vmlinuz-2.6.28-11-generic
> root=UUID=3403d691-06fd-4646-840c-8f936fd99ab9 ro quiet splash
> initrd          /boot/initrd.img-2.6.28-11-generic
>
> title           Ubuntu 8.04.1, kernel 2.6.24-24-generic (on /dev/sdb2)
> #root           (hd1,1)
> uuid            9c17f912-7f27-40c4-a8c2-141924762217
> kernel          /boot/vmlinuz-2.6.24-24-generic
> root=UUID=9c17f912-7f27-40c4-a8c2-141924762217 ro quiet splash
> initrd          /boot/initrd.img-2.6.24-24-generic
>
> I stress again that pair of stanzas in question in both  menu.lst files are 
> copies
> of each other. I have confirmed this by diffing them.
>
> I *can* boot from IDE disk's MBR the Ubuntu 8.04 install,
> but *cannot* boot the Mint install.
> Opposite is also true, i.e. I *can* boot from SATA disk's MBR the Mint 
> install,
> but *cannot* boot the Ubuntu install.
> In both failure cases, I get "Error 15: file not found."
>
> In other words, I can boot both Linux installs from the MBR that was setup by
> that very install. No problems. However, neither of them can boot the other 
> install.
>
> Since the stanzas are the same, and one MBR boots each install successfully,
> all files must be where they should be, and the error message is bogus.
>
> So, to switch between these two Linuxes, I am forced to change boot order
> from BIOS everytime. Pain in you know where. :-(
>
> I know it should not be necessary but, I even re-setup the SATA MBR after I
> added the Ubuntu 8.04 stanza. Needless to say it did not help.
>
> What am I missing?
>
> Thanks in advance.
>
>
>
> _______________________________________________
> Help-grub mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/help-grub
>

Your problem is most likely caused by an over-helpful BIOS which is
re-mapping physical devices so that whichever device is selected as
the 'boot' device is setup as the 0th BIOS drive.

In this case for one of the two grub installs you must refer to the
drive your Linux installs are on by some other name; very likely by
using a custom device.map file to specify that (hd1) is actually
/dev/whatever.

Thus one drive would be installed as normal.
The other drive would be setup (manual grub install) with a device-map file.

Since the device-map file would re-define the hard drives the actual
grub.conf file can be the same for both installs.