[dm-crypt] LVM on LUKS: volumes missing

Arno Wagner arno at wagner.name
Fri Jun 3 23:42:20 CEST 2016


One thing is that these problems are pretty hard to debug.
Another is that LVM massively complicates things.

Now, if the LUKS container opens cleanly, anything
in it should be decrypted correctly (if it is LVM
atop of LUKS) and decryption with the wrong key is
not actually a possibility. 

That also means you should be able to use LVM
recovery techniques (I assume they exist) on this.

Unfortunately, I cannot help you with LVM as I do not use 
it. I consider it a badly engineered, overly complicated 
thing that decreases reliablity and makes problem 
diagnostics very hard.  Unfortunately, it provides some
increases in convenience and that seems to be all most people
care about, atleast until they are confronted with the hard
realities of reliable engineering, namely that KISS
is more important than any other concern. As LVM
violates that (along with the new RAID superblock
formats, udev, systemd and some other engineering 
abominations that have found their way into mainstream
Linux recently) I do not tolerate LVM on any of my
systems. 

Regards,
Arno


On Thu, Jun 02, 2016 at 14:57:57 CEST, fauno wrote:
> On 31/05/16 11:54, fauno wrote:
> > On 31/05/16 09:52, Robert Nichols wrote:
> > 
> >> Take a look at the decrypted volume with "hexedit -s". It should start
> >> out with mostly binary zeros with a little data including the ASCII
> >> string "LVM2" at the start of a few of the sectors. Starting at about
> >> the 10th sector there should be a lot of ASCII text. (It's a copy of the
> >> corresponding file in /etc/lvm/backup, though without the fancy
> >> formatting.)
> >>
> >> If you're seeing random-appearing binary junk there, then the volume is
> >> not be decrypted properly. If it's just some of the early sectors that
> >> are clobbered and the text starting at the 10th sector is intact, then
> >> this should be recoverable.
> >>
> > 
> > i've tried reading `hexedit` both on the closed and opened partition and
> > everything seems to be random junk.  `strings` also can't find anything
> > resembling LVM data.
> 
> i'm guessing silence means no one wants to give me the bad news :P
> 
> 
> -- 
> :D
> 




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-- 
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

If it's in the news, don't worry about it.  The very definition of 
"news" is "something that hardly ever happens." -- Bruce Schneier


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