Walter Vaughan schrieb:
> IANAL, but unless you have more than 4 gig of memory, you really don't
> get a gain from a 64bit OS vs. a 32bit.

Not entirely true - in practice, gains can start at >2GB.

That's because half of the address space is usually reserved for shared
libraries, which means that if the OS doesn't use the full 2GB, that
part of main memory simply remains unused.

The above isn't entirely correct; current-day Linux kernels can use 3GB
for applications and 1GB for shared libraries and kernel.
IIRC you still need to recompile the kernel to get that feature, and
some RAM will still remain unused.

Adressing all bytes on current-day disks requires more than 32 bits, so
a 64-bit processor is usually a win for a database. A 64-bit OS can make
that easier to do in practice, though in principle, one should be able
to access the 64-bit registers even with a 32-bit OS.

> There are performance hits to
> look past the 4 gig window with a 32bit OS. In a 2 gig box, their is
> almost imperceptable overhead of the 64bit OS, yet you have to also
> endure the lack of hardware driver intergration,

Agreed.

Jo