[CentOS] Manually mounting partitions in "linux rescue" mode
Edward Diener
eldiener at tropicsoft.com
Tue Aug 3 19:08:30 UTC 2010
On 8/3/2010 2:27 PM, James Hogarth wrote:
> I normally use a live CD for this sort of thing... in that case you
> don't need to cheroot at all. Just make sure your
> <rootmountpoint>/boot/grub/device.map is correct and do grub-install
> --root-directory=<rootmountpoint> /dev/sda (assuming you want the mbr on
> sda)
I am booting from the installation DVD. Is that what you mean by a live
CD ? When I boot from that, will it necessarily have a correct
/boot/grub/device.map ?
If not, then mounting my boot and root partitions and doing a chroot was
needed. If so, then I did too much work.
>
> James
>
> On 3 Aug 2010 18:21, <m.roth at 5-cent.us
> <mailto:m.roth at 5-cent.us>> wrote:
> > Edward Diener wrote:
> >> On 8/3/2010 11:13 AM, Les Mikesell wrote:
> >>> On 8/3/2010 9:56 AM, Edward Diener wrote:
> >>>>
> >>>> I am at the shell prompt but in order to get grub to work, don't I
> need
> >>>> to mount my actual boot and root partitions for grub to know that
> >>>> (hd0,9) refers a valid boot partition when I tell grub:
> >>>>
> >>>> root (hd0,9)
> >>>> setup (hd0,9)
> >>>
> >>> No, grub doesn't need to have anything mounted.
> >>
> >> OK, thanks for the info.
> >>
> >>> The sysimage mount and
> >>> chroot is most useful to get access to your usual tools in their usual
> >>> paths and to be able to edit the grub.conf file. I've never tried to
> >>> boot from a partition that far into the disk, though. I had enough
> >>> trouble back in the days when bios only knew 1024 cylinders that I've
> >>> always put a small /boot partition as the first thing on the disk even
> >>> though you shouldn't have to now.
> >>
> >> My problem was that once I did a chroot I did not have any /dev devices.
> >> Evidently grub does use this. Once I did:
> >>
> >> mount --bind /dev /mnt/sysimage/dev
> >>
> >> before doing:
> >>
> >> chroot /mnt/sysimage
> >>
> >> when I executed 'grub' it found the (hd0,9) partition.
> >
> > "Executed grub"? Not chroot, then grub-install /dev/sda?
> > <snip>
> > mark
> >
> >
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