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sibir

Member

Registered: 2025-02-09

Posts: 3

cloned drive boots only to fallback

I have 2 supposedly identical (industrial) PCs, one is working and I want to turn the other into a clone (for emergency replacement).
So, I cloned the drive, but on the second PC I can only boot to the fallback image.

If I compare /etc/mkinitcpio.conf (after booting into the regular image on the old and into the fallback on the new PC), both appear to use the same HOOKS.
What else could be different between the fallback and the regular images?

Last edited by sibir (2025-02-09 21:21:12)

Scimmia

Fellow

Registered: 2012-09-01

Posts: 13,725

Re: cloned drive boots only to fallback

They aren't identical, then

cryptearth

Member

Registered: 2024-02-03

Posts: 2,130

Re: cloned drive boots only to fallback

if cloning doesn't work the systems seem to be more differentvthan you think
how about simply install from scratch

sibir

Member

Registered: 2025-02-09

Posts: 3

Re: cloned drive boots only to fallback

I will dig deeper comparing the 2 PCs.

But I am curious why the fallback boots and the regular initramfs image does not.

Looking at  /etc/mkinitcpio.conf after booting into fallback I expected more HOOKS, but they are the same:

HOOKS="base udev autodetect modconf block filesystems keyboard"

Last edited by sibir (2025-02-09 21:27:07)

Scimmia

Fellow

Registered: 2012-09-01

Posts: 13,725

Re: cloned drive boots only to fallback

The fallback eliminates the autodetect hook, including all drivers instead of just those in use on the computer it's being built on.

sibir

Member

Registered: 2025-02-09

Posts: 3

Re: cloned drive boots only to fallback

Thank you, that is interesting. So, autodetect detects only at build time or when mkinitcpio is run, not at boot? Is there a list of what has been detected?
I can run mkinitcpio -M to see what is currently detected, but that may not reflect what's in initramfs.img

Last edited by sibir (2025-02-10 00:13:12)

cryptearth

Member

Registered: 2024-02-03

Posts: 2,130

Re: cloned drive boots only to fallback

just a guess but for a system to boot there are not many drivers needed - mostly storage drivers as after them got loaded the boot environment can mount the real root and load additional stuff from there

another option: please check your boot config for the root uuid: unless you cloned the drive byte-per-byte the partition table and filesystems will have different uuids
if you just copy over a foreign config its uuids doesn't match the ones on the drive which usually leads to some error like "real root not found - drop to emergency shell" or similar

as for how the fallback works different in that manner - i don't know, but could be related

Last edited by cryptearth (2025-02-10 09:50:35)

jonno2002

Member

Registered: 2016-11-21

Posts: 856

Re: cloned drive boots only to fallback

its all in the wiki

Regenerate kernel image

It is recommended to regenerate the initramfs image, although initially the fallback initramfs image may work.