[lug] Multi OS booting

[D. Stimits]

David L. Anselmi wrote:
> William Petty wrote:
> 
>> If I stay "ALL" SCSI, I may go back to an old trick I used to do. I just
>> add a switch somewhere on the front panel and tie it to a higher ID 
>> jumper
>> on the lowest drive.  Flip the switch and the drive boot order 
>> reverses.  Of course it gets ugly with lots of drives or SCA backplanes.
> 
> 
> All I've ever done is install Windows on the "first" drive/partition. 
> Linux doesn't care.  Sorry, I don't rearrange drives much but if that 
> makes Windows painful, just don't do it.  Make it first and leave it alone.

Mine has always been the first drive. Using the windows boot loader. 
It's in a removeable bay so I literally just pop it if I don't want it 
there. The reason behind it is a long one, and it was NOT as simple as 
just installing things where I wanted at the moment...strongly related 
to drive upgrades over time.

> It doesn't really matter which loader you use.  I've let Windows run the 
> hda MBR and put LILO on a floppy's MBR.  No floppy, Windows boots and no 
> one knows Linux is on the box.  Put in the floppy and Linux boots.

I don't want to depend on a floppy...I simply won't go that route. I can 
pop the hard drive out as easily as a floppy though, due to the 
removeable bay.

> I don't see why booting Windows from GRUB would require drive hiding. 
> Sorry if I'm missing your point.

It would require drive hiding if you don't want windows to be the first 
drive. The reason I don't want windows as the first drive is because I 
have an extremely strong distrust of how windows deals with foreign boot 
loaders...to say the least windows has managed to annoy me changing 
things around in the past to the point of some cussing. Windows and I 
have a history...not a good or pleasant one. Now if linux were on the 
first drive and the drive could be hidden, then windows would never muck 
with it. In fact this is a small part of why I pop a drive out when 
running windows...I don't want windows to have any ability to format or 
"fix" drives it thinks are broken (but which are really just linux drives).

I may risk it anyway, by putting grub on the MBR of the first drive with 
the first drive being windows. Using the NT boot loader (it's win 2k) 
requires putting a kernel image on the NT partition (I won't do it), so 
that's out...it *must* work with grub before I'll even think about it. 
But for the only examples I've known of using grub to boot windows it 
has been as a chain loader which points at the MBR of a non-first-disk 
windows install (which is a feat in itself...it can be done playing 
tricks with scsi controllers since windows has no ability to install or 
see a 2nd chain during an install process until it is long past the boot 
loader install). In all of those cases the MBR of the first disk was NOT 
windows boot loader, but windows did have the MBR of the drive it was on.

>> P.S. Have you ever reverted a machine from grub back to lilo?
> 
> 
> Yes, it's trivial.  Just remember that it's what's on the MBR that runs 
> when booting, that "lilo" writes LILO to the MBR, and that grub-install 
> writes GRUB to the MBR.  You might save yourself some headaches by 
> ignoring the partition boot sectors and only using the drive boot 
> sectors (i.e., install only to sda, never to sda1).  And if you can 
> manage to keep one drive "first" you only ever need to install to that 
> boot record.

As long as you don't change the drive geometry you can also backup the 
MBR with dd. On x86 it's just a single block of size 512.
dd if=/dev/hda of=/tmp/backup_mbr.iso bs=512 count=1

You can restore it with the reverse.

D. Stimits, stimits AT comcast DOT net