However, I have found that I am unable to access the LUKS partition
when the system is under heavy load and swapping.
Martin, I wonder if this has anything to do with the virtual memory
bug in the kernel that we experienced with apt. It could be that this
bug existed before 2.6.19 but was much harder to trigger (e.g. see
http://lkml.org/lkml/2007/1/3/285). It would be interesting to try
accessing a LUKS partition under heavy load while running 2.6.20-git,
but that will have to wait until the weekend for me to test it.