Hello,
I'm struggling to make a cloned CentOS 7 VM (under KVM) to work.
The VM was cloned using mondorestore. Restore appears successful but the
VM won't boot; see:
http://iweb.noa.gr/files/centos7/supergrub2-scratchvm-20170503-04.png
I booted with CentOS 7 disk in troubleshooting mode (where the virtual
disk was automatically mounted without issues) and I tried to repair:
http://iweb.noa.gr/files/centos7/el7-rescue-scratchvm-20170502-01.png
Also:
# grub2-mkconfig -o /boot/grub2/grub.cfg
...
/usr/sbin/grub2-probe: error: unknown filesystem.
I then tried to repair using:
https://sourceforge.net/p/boot-repair-cd/home/Home/ but it didn't manage
to solve the problem. (It reported success but the VM still won't boot.)
More interesting was the effort with the supergrub2 disk:
http://www.supergrubdisk.org/super-grub2-disk/
This managed to identify the available "boot methods" and allowed me to
boot correctly. See screenshots:
http://iweb.noa.gr/files/centos7/supergrub2-scratchvm-20170503-00.png
http://iweb.noa.gr/files/centos7/supergrub2-scratchvm-20170503-01.png
http://iweb.noa.gr/files/centos7/supergrub2-scratchvm-20170503-02.png
Once I logged in, I checked /etc/fstab and /boot/grub2/grub.cfg but I
didn't see any obvious problem. The are here as well:
http://iweb.noa.gr/files/centos7/fstab
http://iweb.noa.gr/files/centos7/grub.cfg
However, I also followed these directions:
https://www.techbrown.com/reinstall-grub2-boot-loader-centos-7-rhel-7.shtml
to rebuild grub2.conf. The commands were completed successfully.
Unfortunately, the OS still won't boot: same issue, see:
http://iweb.noa.gr/files/centos7/supergrub2-scratchvm-20170503-04.png
I again tried to boot using the supergrub2 disk; this time the boot
method detection produced the (slightly different) list you see in image:
http://iweb.noa.gr/files/centos7/supergrub2-scratchvm-20170503-05.png
Using the supergrub2 disk I can boot and login successfully. Otherwise
(i.e. directly) the box won't boot.
As I know little about grub2 (and low-level linux) to troubleshoot the
issue, can you please help identify and correct the problem? Why the VM
always refuses to boot?
Which is the reported device (on image -04) that remains unrecognized? I
looked into /boot/grub/grub2.cfg but I didn't see any such UUID there.
Where may it be referenced to be used during the boot process?
Note: I never have such issues when restoring (using mondorestore)
CentOS 5 or CentOS 6 mondoarchive backups (even on dissimilar virtual
hardware).
Can you please help me identify the problem, based on the above info,
and make the VM normally bootable?
Many thanks,
Nick
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