[dm-crypt] LVM on LUKS: volumes missing

Robert Nichols rnicholsNOSPAM at comcast.net
Tue May 31 14:52:20 CEST 2016

On 05/30/2016 04:54 PM, fauno wrote:
> Hi, maybe I'm too shocked but I couldn't find anything on this issue :)
> I have a fully encrypted HD using the LVM on LUKS method from
> ArchWiki[^0], with the LUKS header and key file on an external device.
> Today I started having some disk failures (root remounted ro, xfs
> partition giving errors), and after I decided to reboot to run fsck, I
> can't find anything.
> When the encrypted partition is opened, I don't see any errors, not even
> on dmesg, but LVM can't find any volume.  They're just missing.

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.

Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.

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