Re: [LUG] Problems with debian testing - cannot boot. ii

[comrade meowski <mr.meowski@xxxxxxxx>]

On 26/10/2020 19:43, Henry Bremridge wrote:
> On 26/10/2020 19:37, comrade meowski wrote:
> > On 26/10/2020 19:22, Henry Bremridge wrote:
> > > > Running sysrescue from usb
> > > I can see all files, (I have a separate partition for home)
> >
> > Unless you're very familiar with working on chrooted systems to repair
> > them you'll be better off initially returning to letting the system
> > (fail to) boot under it's own power again. When you reach the
> > emergency shell give it the root password to login and commence
> > information gathering.
> >
> > Having a look at the output of:
> >
> > systemctl --failed
>
>    UNIT        LOAD   ACTIVE SUB    DESCRIPTION
> ● vdr.service loaded failed failed Video Disk Recorder
>
> LOAD   = Reflects whether the unit definition was properly loaded.
> ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
> SUB    = The low-level unit activation state, values depend on unit type.
>
> 1 loaded units listed.
>
>
> > journalctl -p err -b
>
> $ journalctl -p err -b
> Hint: You are currently not seeing messages from other users and the system.
>        Users in groups 'adm', 'systemd-journal' can see all messages.
>        Pass -q to turn off this notice.
> -- Logs begin at Sun 2020-02-23 07:45:04 GMT, end at Mon 2020-10-26
> 19:41:04 GMT. --
> -- No entries --

> Booted in kernel 4.16, seems to have fixed it. Running back up again

"Sidestepped it" seems more accurate here but at least the system is 
running normally again, so that's a win.

Now it's functional dig deeper to find out what happened and correct it. 
Might have been a failed upgrade to the kernel and bootloader which you 
should rerun - kernel 4.16 is comically out of date.

https://packages.debian.org/bullseye/linux-image-amd64

Generic kernel package for your system is linux-image-5.9.0-1-amd64 so 
your system is running a weird configuration. I'd recommend running:

sudo apt-get install linux-image-generic --install-recommends

And checking through what it wants to do before letting it install the 
current kernel and support packages.

Examine the last few boot entries worth of errors by checking your 
previous boots:

sudo journalctl --list-boots
sudo journalctl -p err -b

Then run 'sudo journalctl -p err -b X' to list the errors from 
respective boot attempts. '-b' with no argument shows the previous boot, 
increment by 1 for each previous boot you want to display from so:

sudo journalctl -p err -b       #current boot
sudo journalctl -p err -b 1     #previous boot
sudo journalctl -p err -b 4     #4 boots ago

Make sense? Skim a basic journaltctl primer for more info on how to 
filter logs if you like, it's a pretty useful skill. You're looking for 
something that stands out as an obvious failure in the couple of boot 
logs where the machine failed to start correctly in between it's 
successful boots. Should be super obvious.

systemctl status vdr

Will tell you why your single current failed service isn't working as well.

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