On Mar 19, 3:04 pm, "Magnate" <n...@receiving.here> wrote:
> "eric" <questermoco...@hotmail.com> wrote
>
> > Hi all,
> > I have an external disk with Linux, and Windows on the internal disk
> > of my laptop. I have GRUB installed on the external disk, so I can
> > boot either Linux or Windows. This used to work just fine.
> > Lately I have been having lots of problems in loading GRUB. Most of
> > the time it doesn't load and the machine just boots Windows from the
> > internal disk. It seems to be getting worse with time.
>
> The problem is unlikely to be time-related. Either the machine boots from
> the external disk or it doesn't. If it does so but only intermittently, the
> problem is far more likely to be cable-related than anything to do with the
> contents of the MBR or the disk itself. IME of course.
>

Thanks a lot for your reply. I was able to load GRUB on the external
disk on two other
machines. I only made one attempt on each machine and it worked for
both, while on
the laptop it's still intermittent. I begin to think it's a power
problem, namely the USB
port doesn't give enough power to the disk at the beginning. I tried
also to use the
extra USB power cable (in addition to the data cable) but it's still
intermittent.


> > When I boot another linux on a different machine, I can read and write
> > on this external disk, so the disk is not broken. I don't think it's
> > a problem with the BIOS either (boot order seems fine, plus I tried
> > with another laptop and got the same problem).
>
> So you cannot boot from this disk at all? Or you can on another machine? Or
> it boots intermittently on either machine?

See above.
>
> > Questions (I've googled around but I still can't figure them out):
>
> > 1. could it be a software problem with the MBR? If so, how do I fix
> > it?
>
> I guess it's not impossible. You fix it by re-installing GRUB to that MBR
> (grub /dev/sdx where sdx is the external disk).
>
> > 2. if it's a hardware problem (heads cannot read the MBR?), is it
> > possible to install GRUB on a USB key and from the USB key boot
> > Linux on the external disk and Windows on the internal disk?
>
> AFAICT there is no way to do this, because when GRUB is run from the USB
> key, it is only aware of the USB device, so it cannot boot a partition on
> another device. This could be wrong - but I have never seen or heard of a
> solution.
>

I was under the impression that once GRUB is loaded into the computer
memory,
it doesn't matter where it was residing. For example when I manage to
load GRUB
residing on the ext. disk, I can boot the Windows installation
residing on the internal disk.
Am I missing something?

Thanks again.

> You could consider installing GRUB on the laptop's *internal* disk though.
> It should then offer you the ability to boot from either disk, as you
> choose. This would not solve the problem of why you can no longer boot
> (consistently) from the external disk, but would work around it.
>
> CC