LUKS overhead (was Re: encrypted root fs on a slug and crypto-modules)
On Sun, Mar 09, 2008 at 11:54:29PM +0100, Anders Lennartsson wrote:
> As a further note on the subject of this thread, I did manage to
> install Debian Etch on a fully encrypted USB-stick (1 GB) with two
> partitions, one for root and one for swap. I used default settings for
> LUKS encryption which I belive is 128 bits. My impression is that it
> didn't really affect performance but I have not made any objective
> tests of this.
I built a 2.4.24 armel system on my Thecus N2100 last night, and created
a 100GB data partition to test this out. There are a few layers
WDC5000KS -> md (raid-1) -> lvm2 -> dm-crypt -> ext3 -> smb
That's two more (lvm2; dm-crypt) than I'm used to on this machine.
Copying a few GB onto the device via SMB resulted in kcryptd consuming a
lot of CPU for several minutes after each transfer. I'm not sure if it
impacted the speeds much, I got ~1.5MB/s which is far from great
(100-base-t switch is the limiting factor ethernet wise) but I was
getting roughly that (mostly over SSH rather than SMB) beforehand (with
the old ABI).
The machine didn't boot this morning, but if it does when I get back
from work, I'll try and get some more figures on how much of an overhead
I'd expect things to be worse on the slug than the n2100.