Encrypted root on Fedora 13

Hi,

is there any possibility in cryptsetup-1.1.3 to maintain / restore the uuid of an encrypted root partition on a Fedora 13 system?

What I've planned to do is to switch the standard encryption the Fedora installer has put on a laptops root partition from aes-xts-plain to twofish-xts-plain, because twofish is about 25% faster on this machine. So I'll boot from CD, take a copy of the root fs, reformat it with the new specs, and restore from backup.

However, the uuid of the partition gets changed by this process, and I'm curious if writing the new uuid into fstab/crypttab/grub.conf is enough to boot the system properly.

I tried to chroot into the Fedora root directory from the boot CD and rebuild the initramfs via dracut, but the root partition could not be found any more. I guess the uuid of the encrypted root partition is included in the initramfs, which means that I have to build an initramfs from the active system, which isn't possible.

So is there a possibility (maybe in cryptsetup) that allows to customize the uuid? It's possible with xfs_admin to do that, but only the uuid of the mapped partition, the uuid of the device itself doesn't get changed, of course.

What am I missing?

Thanks,
Heinz.

I think I added UUID into API (so you can specify UUID when formatting drive) but I probably forgot to add it to CLI (cryptsetup binary) yet.

But there should be also way how to change it later.
(I saw that request for other things - like changing UUID of LUKS snapshot.)

If you want to track this, please add issue to cryptsetup page. I am just trying to fix some long term requests for new release, this is one of candidates to fix.

But because UUID is encoded in header as string, you can probably easily modify it using hexaeditor as workaround for now.

You can always extract initramfs, change it inside and compile it again. (it is just cpio.gz archive)
(I have no encrypted fedora handy unfortunately to check whats needed.)

For now, I suggest to boot into dracut shell, activate system manually (singleuser is ok) and recreate ramdisk.

see http://fedoraproject.org/wiki/Dracut/Debugging and
http://sourceforge.net/apps/trac/dracut/wiki/manpage

It should be 5 minutes job if you know how to do it:-)

Milan

Thanks a lot for your help, Milan!
I guess I'll do it that way, this is quite ok for me :-)

Thanks,
Heinz.

Huh, did it, that was easy and effective, worked great. Thanks again ;-)