I don't see why you would want to use User Mode Linux for OpenACS
hosting. Yes, it should work, but you're running an entirely separate
Linux kernel for every virtual server. Unless you really
need custom kernels for each customer - extremely unlikely -
that's massive overkill, and I assume performance would suck because of
it.
Acorn Hosting uses the Linux
VServer
kernel patches instead, which is basically the exact same idea as
FreeBSD's jail facility. All virtual servers share one kernel, but
everything else is virtualized. Should be significantly faster than
UML.
This stuff has been discussed here previously, at least in
June 2003
and
Oct. 2001.