Re: How to install grub on fakeraid (raid 0) which spans 2 TB?

[Bruce Dubbs <bruce.dubbs@gmail.com>]

André Heynatz wrote:
>> P ntfs  300 GB Windows XP SP3 32 Bit
>> P ntfs  300 GB Windows 7 32 Bit
>> P ext2  100 MB /boot
>> E
>> L swap    2 GB Linux swap
>> L ext4  250 GB Ubuntu Linux 9.10 (Karmic) 32 Bit
>> L ntfs 1100 GB data (for data exchange and storage)
>> L ext4   48 GB spare space for testing of new OSes

> I have applied the partition table mentioned above. Windows 7 Disk
Management Tool does not allow to create an Extended Partition on the
third Primary partition slot. Thus I used the Ubuntu installer to do it.
At first I tried to install GRUB2 from Ubuntu 10.10 (Lucid), but the
error message remains :-( Then I tried GRUB1 and succeeded, luckily.
Probably there is a problem with the sector offset or the data partition
is too large for GRUB1 to skip over. It is > 1 TB. In the actual scheme,
the 1.1 TB data partition comes after the root partition (where GRUB is
installed).

> After a kernel update I have to call 'update-grub' manually, but I am
 > happily doing this, it is only a minor glitch of Ubuntu 9.10.

> If there is a new version of GRUB2 which supports dmraid devices, I
happily test it. Maybe it is only a configuration issue, as GRUB2 has
become quite flexible.

If you would like to test GRUB2 without installing it on the MBR, you 
can do that.  Assuming that your drive is /dev/sda,  you can try:

grub-install --grub-setup=/bin/true /dev/sda

This creates the files needed by your system in /boot/grub.  You can now 
backup your /boot/grub/grub.cfg and try this instead:

### grub.cfg
set default=0
set timeout=15

insmod ext2
set root=(hd0,3)

menuentry "Ubuntu, with Linux 2.6.31-14-generic" {
     search --no-floppy --fs-uuid --set \
               9f8c8d2f-0f67-454c-aec0-affd8fa02fe9
     linux   vmlinuz-2.6.31-14-generic \
                 root=UUID=9f8c8d2f-0f67-454c-aec0-affd8fa02fe9 ro
     initrd  initrd.img-2.6.31-14-generic
}

menuentry "Windows 7 (loader) (on /dev/mapper/isw_bfacafefej_Volume01)"
{
     insmod ntfs
     search --no-floppy --fs-uuid --set 022834062833f6ef
     chainloader +1
}
### end grub.cfg

I took the entries above from your original post.  The continuation 
lines should work, but I haven't tried that.  I didn't want them to wrap 
in this post.  Note that since /boot/grub is a separate partition, we 
omit '/boot' from the start the linux and initrd lines.

Now if you reboot to grub legacy, you can drop to the grub command line:

grub> root (hd0,3)
grub> kernel /grub/core.img
grub> boot

If it works, great.  If not a simple reboot gets you back to grub legacy 
without changing the MBR.

To install GRUB2 on the MBR, just:

   grub-setup /dev/sda

Note that this procedure bypasses the distro setup.  If you update the 
OS automatically, the distro will probably overwrite the grub.cfg file 
when it runs grub-mkconfig, possibly via the grub-pc script.

   -- Bruce