[dm-crypt] Debian 7.10 random key swap Device /dev/sda2 is not a valid LUKS device.

Milan Broz gmazyland at gmail.com
Wed Apr 6 07:38:15 CEST 2016

On 04/06/2016 06:25 AM, David Christensen wrote:
> dm-crypt:
> I have a Debian 7.10 (Wheezy) computer with a random-key swap device. 
> The disk and swap are working.
> When I try to backup the LUKS header:
>      # cryptsetup luksHeaderBackup /dev/sda2 --header-backup-file 
> luksheaderbackup-sda2.bin
>      Device /dev/sda2 is not a valid LUKS device.
> Is this expected/ normal behavior for a dm-crypt/ LUKS random-key swap 
> partition?

LUKS device cannot be used with random volume key, so I guess you use
just plain device without header. (So obviously header backup fails because
there is no header.)

You can verify it by checking entry in /etc/crypttab - no luks keyword:

> # grep sda2 /etc/fstab
> /dev/mapper/sda2_crypt                    none                    swap 

or running "cryptsetup status sda2_crypt" over unlocked device
(type is LUKS1 for LUKS devices)


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