[lug] GRUB

Stephen Queen svq at peakpeak.com
Wed Jul 30 11:42:45 MDT 2003

Stephen Queen wrote:

> I am working on an embedded system that has 2 hard drives, hda and 
> hdb. There is only one partition on each. They are both on ide0. hda 
> is the master, hdb is the slave. I would like to install grub such 
> that if hda is missing hdb will boot. If hda is present, then the 
> system boots from it. I believe that the bios supports this. If it 
> does, how do I setup grub so that this will occur? I have no problem 
> installing it on hda, it is hdb that doesn't seem to work. Is this 
> even possible?
> Thanks,
> Steve
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For anyone who maybe interested, this is what I _think_ I have learned 
regarding this problem. If anyone knows different, please correct me.

The MBR on the master hard drive (HD) is the only place that the boot 
loader works from. You can install a boot loader on the slave HD but it 
will not load as long as that disk is in slave mode.

So to get a work around, I place both hard drives into the cable select 
mode. The way this works is that the drive that has pin 28 of the cable 
connected to the EIDE controller is the Master. The HD that has pin 28 
open is the slave. So to be able to select manually which is the Master 
and which is the slave, I will run pin 28 from the controller thru a 
switch. That way just before power is applied, the HD that will be 
master can be selected.

Thanks for the responses,

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