Alexander V. Makartsev wrote on 1/28/26 10:55 AM:
On 1/28/26 02:32, D. R. Evans wrote:
...
It turns out that the BIOS on the computer doesn't seem to provide any
way to boot from USB. The best I can do, as far as I can tell, is to
create a live DVD and boot from that.
So I have booted from a live CD (which is very slow, but does
eventually succeed), and made sure that the only hard drive in the
machine is the RAID device that I am trying to fix.
That is strange, how old is your hardware? When you mentioned 2013 I was
thinking 4th gen Intel CPU and Haswell-era hardware, which should
support USB-boot.
OK... on the basis of the fact that you expected USB boot to work, I just went
and spent some time messing with the boot options, and found a way to make it
work. What I had not realised was that it was not enough to select "USB-HDD"
from the BIOS list, but I also had to then go and look at the hard drive boot
order, where a new entry had appeared (at a low priority). Once I saw that and
changed its priority so that it was the preferred boot device, the machine
booted fine from the USB drive.
All this, I'm sure, is very elementary stuff... but if one has never
encountered it before, as I have not, none of it was obvious.
So the next bit of your e-mail (about the motherboard and booting) no longer
applies.
...
_Exactly_ what chroot command do you want me to type at this point?
I am sorry I wasn't more clear. What I meant to say is that you have to
get the output data from the OS you trying to rescue, not the host OS.
In other words, after you change root "/etc/fstab" will point to fstab
on the RAID disk you trying to rescue, and if you don't it will point to
fstab of the host system on non-RAID disk.
So "to chroot" means the same sequence of commands as before, but
without grub-install:
mkdir /tmp/RFS
mount /dev/md126 /tmp/RFS #Mount root filesystem
mount --bind /dev /tmp/RFS/dev #Mount bind real /dev to populate
chroot-ed /dev
mount --bind /proc /tmp/RFS/proc #Mount bind real /proc to
populate chroot-ed /proc
mount --bind /sys /tmp/RFS/sys #Mount bind real /systo populate
chroot-ed /sys
chroot /tmp/RFS /usr/bin/bash #Change root into directory /tmp/RFS
Now you can issue those commands and get output:
cat /etc/fstab
cat /boot/grub/grub.cfg | grep -iE -- "--set=root|root=|insmod"
Here's the output of those commands:
https://paste.debian.net/hidden/8c62fe17
I'll pause there, so you have a chance to look at that, and I have a chance to
look at the grub rescue stuff ... and also try put out another (unrelated)
urgent fire.
Doc
--
Web: http://enginehousebooks.com/drevans
