Choosing and Configuring Hardware - Professional SQL Server 2005 Performance Tuning - page 163

What follows is a short introduction to these different processor families along with a short discussion of
some of the factors that influence making a decision on which processor you should use.

32-bitx86Processors
32-bit systems are fast becoming replaced by 64-bit systems. About the only reason for purchasing
a 32-bit system today is cost, and the clear knowledge that the system will never need more than 2 to
4 GB of physical memory. In fact you would find it very hard to find new 32-bit-only processors these
days so your decision is really about whether or not to run 32-bit or 64-bit software.

Multi-Core
A common interpretation of Moore's Law is that processor power will double every 18 months. That
has pretty much held true since 1975 and can be seen in the increase in processor speed over the years.
However, it wasn't expected to continue forever and the processor manufacturers have now pretty much
reached the physical limitations of the processor components, resulting in maximum speeds of about 3.8
to 4.0 GHz. The big question now is how to significantly increase processor performance when you're
unable to increase processor speed. The answer appears to be multiple CPU cores.

Multi-core effectively means more than one CPU on the same chip so when you buy a dual-core processor
you're actually buying two CPU cores, Windows will see two CPUs, and you should treat it for capacity
planning purposes like two single-core CPUs. It gets even better from a licensing perspective because
Microsoft per-processor licensing is per socket, not per core. Socket refers to the physical socket that
you plug the processor into (see Figure 6-9 for an illustration). This licensing model gives Microsoft
a competitive advantage over its competitors in the database market, where others charge customers
a license fee per core. This is great news for SQL Server customers because a server with four dual-core
CPUs will perform comparably with an eight single-core server but at half the license cost.

0 1 Socket

CPU Core

Figure 6-9

At the time of writing, quad-core CPUs are available but not really mainstream and 8-core CPUs are on
the processor manufacturer's short-term roadmap.

Best Practice
Multi-core processors are only licensed per socket so if you can get an 8-core processor
you'll only need a Windows and SQL Server license for 1 socket!