32-bit x86 >4GB RAM

[Lyndon Tiu]

On Mon, 21 Nov 2005 14:15:44 -0700 craigwhite at azapple.com wrote:
> On Mon, 2005-11-21 at 12:07 -0800, Lyndon Tiu wrote:
>
> > Looking for that keyword that allows 32-bit x86 systems to have more 
> than 4GB RAM. Can someone tip me on this so that I can look it up
> Google? Thanks.
> ----
> Why would you use x86 system with more than 4G of RAM?
> 
> Just install appropriate x64
>

Why? I believe it's because:

Cheaper than 64-bit.
Software available in 32-bit only.

What people do is have 32-bit machines with something like 8 GB RAM, then run multiple instances of the same software in a cluster configuration - horizontal clustering. As if you physically have 4 or so regular 32-bit machines running as a cluster, but in this case, you only have 1 physical machine.
 
Part of what I am researching is why people go for these setups rather than full 64-bit systems or even multiple regular 32-bit systems. Are there really performance advantages to these 32-bit >4GB setups?

--
Lyndon Tiu