[dm-crypt] "not a valid LUKS device" after distro change

Arno Wagner arno at wagner.name
Fri Aug 22 13:55:16 CEST 2014

On Fri, Aug 22, 2014 at 11:08:56 CEST, Jonas Meurer wrote:
> Hi John, 
> Am 21.08.2014 um 22:46 schrieb John Wells:
> As Arno already wrote, the hexdump from your meant-to-be LUKS container
> on HOME_LV in FINALFRONTIER_VG doesn't look too promising. I've never
> heard about 'GNU Parted Loopback 0' before, but it sounds like something
> caused Parted to overwrite your LUKS header.

Not necessarily. The other container had that in it the one time as 
well, but it fixed itself ...
> Last hope is to find the LUKS header with an offset on the partition.
> Try to search for 'LUKS' by grepping the output of 'strings
> /dev/FINALFRONTIER_VG/HOME_LV'. If you don't find the string 'LUKS'
> followed by something describing your cipher and hash algorithm, I fear
> that this second partition is lost.

I second searching for that. It may not be the only way though.
Easy way to search:

hd <partition> | grep "LUKS"

That gives you hex offset(s) to examine further. 

> According to your hexdump it's not astonishing at all that neither of
> the distros do recognize the FINALFRONTIER_VG/HOME_LV logical volume as
> LUKS container. It simply doesn't start with a LUKS header.
> The question rather is: what action resulted in the LUKS header being
> overwritten. In the past the partition configuration in the Ubuntu
> installer was kind of confusing, and some people trashed their existent
> LUKS containers by reformatting them as new LUKS container, but it
> doesn't look like that happened to you.

I think it is configuration mis-detection and with a randomized
> I don't want to join the rant against modern Linux distros, LVM and MD-1
> format here. In fact there've been quite some serious bugs in Linux
> (vanilla kernel, userspace tools as well as distro implementations) in
> the past, and ranting about how fucked up everything is today compared
> to the good all days doesn't help to fix them. I prefer to isolate,
> identify and fix the bugs and improve the user experience that way :)

I am not ranting about bugs, I am ranting about broken architecture
and KISS violations. Having seens some commercial software 
source code, I do know that there, it often is even worse. There
are just to many peiople creating software that are not good at
it, and FOSS is really no exception.

Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno at wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
A good decision is based on knowledge and not on numbers. -  Plato

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