Re: attempt to read or write outside of disk 'hd0'
On Sat, 6 May 2017 18:12:03 +0200
Pascal Hambourg <pascal@plouf.fr.eu.org> wrote:
> Le 06/05/2017 à 17:19, Joe a écrit :
> >>
> >> However, the ls command I suggested may still be useful to check
> >> GRUB's idea of the sizes.
> >
> > ls (hd0)
> > (hd0): Filesystem is unknown.
> >
> > ls (hd0,1)
> > (hd0,1): Filesystem is ext2. (after several seconds' pause)
> >
> > I'm only getting the grub rescue> prompt, not the grub> prompt.
>
> I expected that "ls" would be the same in normal and rescue mode.
> Obviously I was wrong.
>
> If the GRUB version on the internal disk is the same, you could boot
> from it while the USB disk is connected, and if the BIOS exposes the
> USB disk even though it is not the boot disk (some BIOS do, others
> don't), then you could use the "ls" command in normal mode to check
> (hd1) and (hd1,1).
>
> Also, if you want to check the partition table on the USB disk more
> thoroughly, you can print it (p) in expert mode (x) with fdisk to
> display both LBA and CHS parameters. CHS parameters cannot be used
> beyond 8 GiB and should contain 1023/254/63.
>
>
Thanks, I'll have a go at that later. I'm currently bogged down in a
completely unrelated grub issue on a different (wheezy) machine: I have
an ext4 filesystem which passes fsck fine, to which I can write, but
which grub2 cannot see.
The same grub rescue> prompt, ls can see the partitions, but grub2
cannot read the root one, says 'unknown filesystem'. An attempt to
reload after a chroot assures me that grub-probe cannot read it,
either. The grub-probe installed in the current Knoppix sees it as
'ext2', which may be as much as I can hope for, but wheezy's
grub-probe cannot see it at all, presumably ext4 is too recent for it.
I'm not going to mess about any more, I'll recreate the partition as
ext3. No doubt grub will find a new and interesting error for me then.
--
Joe
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