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

Arno Wagner arno at wagner.name
Wed Feb 10 19:08:57 CET 2010

On Wed, Feb 10, 2010 at 12:43:55PM -0500, M Thomas Frederiksen wrote:
> On Wed, Feb 10, 2010 at 12:14, Arno Wagner <arno at wagner.name> wrote:
> > On Wed, Feb 10, 2010 at 12:00:39PM -0500, M Thomas Frederiksen wrote:
> >
> > There is no "drive unlocking", what happens is that a new
> > device is created which just happens to contain a decrypted
> > version of the encrypted one. They are not associated in any
> > way (except by an LVM mapping that is typically not understood
> > by applications).
> >
> >
> > So either there is a corresponding device in /dev/mapper or
> > not, btrfs does not care where the device comes from. And
> > if you have not done the cryptsetup, then there is no device
> > in /dev/mapper and btrfs cannot use a non-existent device.
> >
> The point is that once the other volumes are added, btrfs will need three
> devices in /dev/mapper:
>    1. /dev/mapper/sda3_crypt
>    2. /dev/mapper/sdb2_crypt
>    3. /dev/mapper/sdc2_crypt
> However, during the boot process, /dev/mapper/sda3_crypt is the only device
> being created.  If I do a blkid, I get:
> /dev/mapper/sda3_crypt: UUID="e0948aa0-efab-4449-938d-6d74b6ccbf93"
> UUID_SUB="b3b1e4cc-ca0e-44ba-be35-32405b20025b" TYPE="btrfs"
> So would I change the fstab from:
> /dev/mapper/sda3_crypt / btrfs error=remount-ro,compress 0 1
> to:
> UUID_SUB=b3b1e4cc-ca0e-44ba-be35-32405b20025b / btrfs
> error=remount-ro,compress 0 1

Why would you, is /dev/mapper/sda3_not fine?
> ?  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.

You may want to look at /etc/crypttab, that could give you the 
option to mount all three with the same passphrase. I have only 
used it to set up encrypted sawp, no idea what it can do in
addition (man crypttab for a description).

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
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans

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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