[dm-crypt] Help! Command failed: /dev/sdd1 is not a LUKS partition

Arno Wagner arno at wagner.name
Thu Feb 11 00:09:37 CET 2010


On Wed, Feb 10, 2010 at 05:23:32PM -0500, M Thomas Frederiksen wrote:
> On Wed, Feb 10, 2010 at 13:08, Arno Wagner <arno at wagner.name> wrote:
> 
> >
> > Why would you, is /dev/mapper/sda3_not fine?
> >
> 
> It's fine at the moment.  But expect it not to work as soon as I add the
> other volumes to my btrfs.  Remember btrfs has a built-in volume manager.
> 
> 
> >
> > > ?  Would that be the same UUID_SUB for other /dev/mapper/sdX_crypts?
> >
> > I don't think so.
> >
> > > And
> > > would grub / boot scripts be smart enough to figure out that it needs all
> > > three device files?
> >
> > Grub is not involved. What your boot script does, I have no idea.
> >
> 
> Grub needs to know how to get the root device(s) setup.

Grub just needs to find the kernel, load it and start
it. That is it. The rest is done by the kernel.
In particular Grub cannot set up any decryption. For that
reason when using encrypted root with Grub, you will
need a small partition that holds kernel, initrd and
Grub files including its configuration. 

The actual root device is passed to the kernel as
parameter, but it cannot be encrypted. What is passed
with encrypted root is the initrd, which contains
the initial root file system, which is a minimal but
working root filesystem with some essential tools and
some scripts. This initial root is then replaced by 
the decrypted root under control of the init system 
in the initrd, i.e. by some scripts in the initrd. 
Grubs job is done when it loaded the kernel and gave it 
its commandline. 

If you want encrypted boot, you need to use TrueCrypt
or the like, which has its own boot code and does not 
need Grub.

Arno

-- 
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno at wagner.name 
GnuPG:  ID: 1E25338F  FP: 0C30 5782 9D93 F785 E79C  0296 797F 6B50 1E25 338F
----
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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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