[dm-crypt] Partiton alignment

Peter Smith peter.smith3882100 at gmail.com
Fri Sep 3 11:31:01 CEST 2010

I have been experimenting further with cryptsetup, and trying to learn
the concepts. So far i have learned that it is much more beneficial to
use LVM and dm-crypt combined. I have decided to use Serpent as
encryption alogrithm, and this results in Payload offset at 3072
sectors or 1536KiB when the argument --align-payload=1024 is passed to
cryptsetup, this is correct according to another post on this list. I
do not fully understand this part but i try to visualize that one LUKS
"unit" is now 1536KiB "wide" or 3 physical 512KiB erase blocks.
Partitions, LVM and everything else is aligned directly to 512KiB or 1
physical erase block. It is not possible to reduce one LUKS "unit" in
size because of keyslot space etc.

Is my storage stack still aligned even that one LUKS "unit" is 3
physical erase blocks wide, or should one LUKS "unit" be exactly
512KiB "wide" (which is not possible) before my storage stack is

I am not sure that my understanding of the concepts is correct, so i
hope that someone can clarify this.

*/EDIT 1898449599*/

Thanks for any suggestions.

More information about the dm-crypt mailing list