Well, I can contribute to the swap file issue. For starters,
everyone always suggests the swap space to be twice the size of your
RAM. There are probably some theories behind that, but I think the
most important argument is always: running out of swap space crashes
your machine (typically), so plenty of swap means your safe. <p>With
kernel 2.4.x that all changed a bit. What I grepped from the
kernel-traffic mailing list, before 2.4.x you weren't required to
use a minimum amount of swap, other than what you need to fulfill
the need of your processes. Due to some reengineering/optimizations
they (Linus, Alan, et. al) introduced a requirement for the swap: if
you have <i>any</i> swap, it must be atleast twice your physical
RAM. If I understand correctly, this has to do with the algorithm
used for reclaiming unused pages. IIRC, this is especially important
for systems that use the swap a lot. If you do not reserve twice
your RAM size, you risk a kernel deadlock. Now don't start panicking
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it also doesn't happen very often. That's what I know about it.
