Re: Bug#823465: dpkg: Won't run at all on i586 Pentium MMX due to illegal instruction
On Thu, May 12, 2016 at 02:10:17AM +0100, Ben Hutchings wrote:
> > If you discover that the package hoses your system then to rollback,
> > shutdown the system to single-user mode, and remount the file system
> > to be read-only, and then use the command lvconvert --merge to restore
> > your file system back to the state of the snapshot. This will consume
> > the snapshot, and leave the file system (presumably ext3 or ext4) in a
> > potentially confused state, which is why you need to do this with the
> > file system remounted read-only. Then reboot, and you're all set.
>
> What could possibly go wrong?
The sysadmin will complain that she doesn't have enough excitement in
her life? :-)
Seriously, I can imagine scenarios where you're rolling a glibc or
bash upgrade where this might not work, but if you're in single user
mode, the most likely failure mode is that the system wedges up and
you have to hit the big red button to reboot.
But yes, doing this in the initramfs makes a lot more sense.
Presumably some file such as /lvm-rollback would get left in the root
file sytem, and so after initramfs mounts the root file system, if it
seems the presence of that file, it will unmount the file system and
do the lvconvert -merge and then remount the root file system.
Cheers,
- Ted
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