Re: Disk mapping confusion with the device command

[Phillip Susi]

I got it figured out.  Someone sugested those two commands but it looks 
like grub only wants you to tell it about the disk device, not the 
partition as well.  It seems that it accepts device(hd0,4) only it 
ignores the ,4 part.  I left out that line and then had to use the 
geometry command to specify the correct geometry for the drive and now 
it's working. 

I'm now using grub to dual boot windows and ubuntu on a sata hardware 
fakeraid raid 0.  If anyone is interested in how, instructions can be 
found here:

https://wiki.ubuntu.com/FakeRaidHowto

Phillip Susi wrote:

> I have an unusual disk setup where the hard disk can not be accessed 
> using the conventional /dev/hda device.  I have been trying to explain 
> the proper mapping to grub, but it looks like it doesn't understand.
>
> I tried to explain the mapping with these commands:
>
> device (hd0,4) /dev/mapper/via_hfciifae5
> device (hd0) /dev/mapper/via_hfciifae
>
> As you can probably guess, the raw disk itself is accessed using the 
> block device /dev/mapper/via_hfciifae and the first extended partition 
> is accessed via /dev/mapper/via_hfciifae5.  This partition is 
> formatted with ext2 and I mount under /boot.  The bios sees 
> /dev/mapper/via_hfciifae as bios block device 0x80, so grub should 
> have no trouble booting from it.
>
> When I issue the root (hd0,4) command I get an error message stating 
> that the partition table is corrupt.  When I enable debug messages and 
> verbose mode, I see a debug message saying that it is reading from 
> /dev/mapper/via_hfciifae5.  It looks like grub is looking for the MBR 
> on the partition block device instead of the disk block device, and I 
> think that is a bug.
>
> Because I explained to grub with the device (hd0) command that it 
> should open /dev/mapper/via_hfciifae, it should look there for the 
> MBR, but it isn't.  Am I doing something wrong or is this a bug?
>
> For reference I am running ubuntu breezy which appears to have the 
> package "grub (0.95+cvs20040624-17ubuntu7)" installed.
>
>
>
> _______________________________________________
> Bug-grub mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/bug-grub