[NTLUG:Discuss] questions about intalling Grub and MBR

[Chris Cox]

Ed Leach wrote:
> William,
> 
> Thanks. I did as you suggest and the machine booted to an MBR on 
> /dev/sdb that knew nothing of /dev/sda. I can't boot to /dev/sda by 
> itself. (I have Fedora on /dev/sda and am installing Knoppix on 
> /dev/sdb. No Windows.)
> 
> So, if I have 3 hard disks each with Grub on an MBR and install a disto 
> on a 4th hard disk and let it install Grub on its MBR, the installer 
> will go to the other 3 HDs and blow away the MBR on each one? This does 
> not seem right. (Master means Master of the machine?)

No... but it will overwrite the current MBR which is whatever the
primary boot drive is (unless directed otherwise).   A lot of this
is very dependent on how configurable the installer is with regards
to it's bootloader.

See answer to your 1st question below...

> 
> I wonder also if it is safe now to manually reinstall Grub on /dev/sda/ 
> and see what happens. This is a test machine, so I wouldn't lose anything.
> 
> 
>> ----- Original Message ----
>> From: Ed Leach <ntlug at levelofdetail.com>
>> To: NTLUG Discussion List <discuss at ntlug.org>
>> Sent: Monday, April 16, 2007 3:23:32 PM
>> Subject: [NTLUG:Discuss] questions about intalling Grub and MBR
>>
>>
>> If I have a distro with Grub on the MBR of /dev/sda and then I install a
>> different distro on /dev/sdb and select to install Grub on the MBR, will
>> it install to the MBR of /dev/sda or /dev/sdb?

/dev/sda by default

>>
>> If it installs to the MBR of /dev/sdb then I assume the machine will
>> boot as before - finding Grub first in the MBR of /dev/sda.
>>
>> Is this right?

Nope.  By default (and I emphasize default), it will go onto the MBR
of the drive that is considered to be the bootable drive (which is
usually the first drive).

Ed... what exactly are you wanting to accomplish?  Maybe we can
suggest a viable scenario for you.