[NMLUG] another boot issue

[ebrown at lanl.gov (Ed Brown)]

Michael,

	Using lilo on the external array is a good idea, I couldn't figure out
how to load grub from grub (using 'chainloader +1' didn't work).  Lilo
makes that easier.  

	But there is still an issue, that I can't figure a way around.  Here is
the (relevent part of the) current grub.conf:

root (hd0,0)
kernel /vmlinuz-2.4.21-9.0.1.EL ro root=LABEL=/  
initrd /initrd-2.4.21-9.0.1.EL.img

The interesting thing is that this configuration works
1. When the external array is unplugged, ie, /dev/sda is the only drive,
the internal drive.
2. When the array IS plugged in, and we go into the regular BIOS and
select the internal drive to boot from.  Remember, in this case,
/dev/sda is assigned by the kernel to the external array, and the
internal drive is /dev/sdb.  So when the internal seagate is selected to
boot from, the BIOS is mapping that as hd0, even though the linux kernel
sees it as sdb. One grub.conf, works in either situation, (IF we select
the second drive in the BIOS). 

If I get the lilo->grub solution working, no more selecting anything in
the BIOS required, but the default grub entry will no longer work,
because now the BIOS will be telling the bootloader[s] that the internal
drive is hd1.  

Ok, it seems like no big deal, to have a second grub entry that has:
root (hd1,0)
but an object of this whole arrangement is a kind of high
availability/redundancy thing: if the server has any kind of problem
(disk,mobo,pwr supply, whatever), the data array (with its own built in
data redundancy) can be simply moved to the backup server, and anyone on
the team should be able to make this switch, without knowing any tricks
to get the server to boot. 

This does seem like the best solution yet though.  I thought of one more
thing to try first.  Maybe not all of the 6 slots for internal drives
are on scsi channel B.  If I could get the internal drive and the
external array both on A, then just changing the id of the array would
solve the problem.  Will let you know.  

thanks again,
Ed 




On Fri, 2004-04-02 at 09:06, Michael Maddex wrote:
> Ed, here's a short description of what I had in mind:
> 
> 1 - With the external array removed, set up the box as usual with grub installed in
> in the MBR of /dev/sda (if that's your first drive, the one the BIOS is finding).
> 
> 2 - With the external array attached, set up the box with lilo installed in the MBR
> of the first drive of the array, the one where the BIOS is now looking for a boot
> loader.  After the usual top lines in /etc/lilo.conf, you should have a single stanza
> something like:
> 
>         other = /dev/sdxn            # where 'x' and 'n' locate your grub loader
>                 table = /dev/sdx     # location of the partition table
>                 lable = somestring   # if you need a boot menu