OT: diagnosis of failure to boot

Reboot stopped at emergency mode.

journalctl -xb does not list any complaints (that I can find), but 
there's clearly something wrong! Any suggestions as to diagnosis?

kernel is 5.7.9.200. selinux is disabled.

livecd boot is OK; disk is accessible.

I saved the output of journlctl, so its available for interrogation. No obvious complaints

Thoughts? Diagnosis?

[George N. White III]

On Tue, 11 Aug 2020 at 11:26,  wrote:
> Reboot stopped at emergency mode.
>
> journalctl -xb does not list any complaints (that I can find), but
> there's clearly something wrong! Any suggestions as to diagnosis?
>
> kernel is 5.7.9.200. selinux is disabled.
>
> livecd boot is OK; disk is accessible.
>
> I saved the output of journlctl, so its available for interrogation. No
> obvious complaints
>
> Thoughts? Diagnosis?

Are you using UEFI Secure Boot?
Was grub2 updated recently?
Is this a multi-boot system?

Other distros, including RHEL, have reported boot failures after applying
updates to grub2 for CVE-2020-10713.

[Geoffrey Leach]

On Tue, 11 Aug 2020 12:00:07 -0300
"George N. White III"  wrote:
> On Tue, 11 Aug 2020 at 11:26,  wrote:
> > Reboot stopped at emergency mode.
> >
> > journalctl -xb does not list any complaints (that I can find), but
> > there's clearly something wrong! Any suggestions as to diagnosis?
> >
> > kernel is 5.7.9.200. selinux is disabled.
> >
> > livecd boot is OK; disk is accessible.
> >
> > I saved the output of journlctl, so its available for
> > interrogation. No obvious complaints
> >
> > Thoughts? Diagnosis?
>
> Are you using UEFI Secure Boot?
> Was grub2 updated recently?
> Is this a multi-boot system?
>
> Other distros, including RHEL, have reported boot failures after
> applying updates to grub2 for CVE-2020-10713.

The problem was a bad ssector on /home. Fsck solved it.

Question: how to fsck on / which is mounted and busy in emergency mode?

[Michael Hennebry]

On Tue, 11 Aug 2020, Geoffrey Leach wrote:
> The problem was a bad ssector on /home. Fsck solved it.
>
> Question: how to fsck on / which is mounted and busy in emergency mode?

I think the answer is you don't.
Boot from a floppy or something and run fsck from there.

[Tony Nelson]

On August 11, 2020 11:23:14 AM EDT, Michael Hennebry  wrote:
> On Tue, 11 Aug 2020, Geoffrey Leach wrote:

...
> > Question: how to fsck on / which is mounted and busy in emergency
>
> mode?
>
> I think the answer is you don't.
> Boot from a floppy or something and run fsck from there.

Boot with the kernel command line option rd.break=pre-mount . See man dracut.cmdline , from man kernel-command-line .

[Cameron Simpson]

On 11Aug2020 08:17, Geoffrey Leach  wrote:
> Question: how to fsck on / which is mounted and busy in emergency mode?

If you don't have a rescue CDROM (or the like) the traditional approach 
is: remount it readonly, then fsck, then reboot.

mount -o remount,ro /

Cheers,
Cameron Simpson