[dm-crypt] Need help with sync'ing dmsetup info to disk

Johann Burkard johann at johannburkard.de
Tue Jul 12 17:30:38 CEST 2011


I have a big problem with one of my machines: Upon booting, there are no  
entries in /dev/mapper and the system doesn't start. It looks like this:

ls -l /dev/mapper
crw------- 1 10, 59 control

Fortunately, I was able to read the dmsetup tables from a backup of the  
disk. They look like this:

sda2_crypt: 0 234241709 crypt twofish-cbc-essiv:sha256  
0000000000000000000000000000000000000000000000000000000000000000 0 8:2 2056
data-drive: 0 216662016 linear 252:0 17572224
data-swap: 0 17571840 linear 252:0 384

Now, I tried a Ubuntu live CD to restore them. I edited the table  
definitions to point to /dev/sda2 (which is the crypto partition) and  
called dmsetup create sda2_crypt ..., dmsetup create data-drive ...,  
dmsetup create data-swap ...

However, once I reboot into the original OS on the disk, the entries are  
gone again.

When I try to create the entries with dmsetup in the initrd, I get this  

(initramfs) dmsetup create sda2_crypt --table '0 1234....'
device-mapper: reload ioctl failed: Invalid argument
Command failed

How can I save the dmsetup tables to disk from the Ubuntu live CD?

Thanks for any help.


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