Hard drive weirdness.

[Rashkae]

David Vincent wrote:
> David Gibb wrote:
>> When I pulled sata drive #1, I get a blank screen with a blinking
>> cursor. No GRUB, no nothing. When I pulled sata drive #2, I get "GRUB
>> Hard disk error". When I pull both disks, I get a "System disk not
>> found" error.
> 
>> I guess my questions are as follows:
> 
>> 1) Does anyone know why my PATA drive isn't showing up as /dev/hda?
>> 2) I guess I could possibly explain the "GRUB Hard disk error" if the
>> absence of a drive caused the drive number to change, but I don't know
>> why the absence of the other drive causes a blank screen.
>> 3) Any idea how I should tinker with this system so that I can still
>> boot it in case one of the raid drives fails?
> 
> my guess is your grub is installed to sata drive #1 (/dev/sda) and your
> sata disk #2 (/dev/sdb) is not set to bootable.
> 
> someone please correct me if this seems too convoluted.
> 
> 1.  you want to install grub to your /dev/sdc so when both disks fail
> grub can still find your stage1 and boot ubuntu.
> 
> boot into ubuntu, open a terminal, type these commands:
> 
> sudo grub
> find /boot/grub/stage1  (pay attention to the output here)
> root (hd0,2)  (i'm guessing that is the output from above, if not use
> what grub spat out)
> setup (hd0,2)
> quit
> 

Actually, yeah, this method is probably easier to get things fixed than
my suggestion.  Only difference is, sdc will not be device 0, but you
need it to be so.

Therefore, between the find and root commands, add this one:

device (hd0) /dev/sdc

when you run the root command, make the device number 0, as above, but
the partition number (the one after the coma) should be the same as
reported by find.

Also, you don't want setup (hd0,2), but rather setup (hd0)  (you want to
install grub in the master boot record of hard drive 0, not any partition.)