Re: Quad Xeon vs. Dual Itanium

Centuries ago, Nostradamus foresaw when DCorbit(at)connx(dot)com ("Dann Corbit") would write:
> Available memory is huge (e.g. you buy a machine with 24 gigs of ram)

Actually, as soon as 2GB of memory starts to feel "restrictive," 64
bit addressing starts being at least nominally worthwhile.

The only way you get Intel 32 bit systems to recognize much more than
that is to get into a mode called "PAE," which (theoretically) offers
the ability to address as much as 64GB.

Unfortunately, it's quite a hack, having considerable likelihood of
slowing your system and possibly not working at all. The slowdown to
be expected is in management of DMA devices (like disk drives).

On the "not working at all" side of things, I can't see that there's
ANY FreeBSD RAID controller that is compatible with PAE, aside from a
Compaq one where the driver author has lately released a warning of
performance problems.

That nicely characterizes the issue that you have to be _real_ careful
about what hardware you buy when going past about 2GB of memory.
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