In a world in which there was no limit to the amount of money you could spend on hardware, you could make a simple decision about the most appropriate hardware: simply choose the level of throughput and reliability you need, and go buy it! Unfortunately, we have yet to discover the location of this kind of world, so your choice of a hardware solution will often be a compromise.
The most commonly implemented hardware architecture for an Oracle server is the SMP system, which strikes a nice balance between power and price. SMP systems are popular for the following reasons:
SMP systems offer more and simpler scalability options for the future than uniprocessor systems.
64-bit processors and operating systems with extended memory support allow SMP systems to handle the needs of very large (even multi-terabyte) databases.
SMP systems have a single operating system and a single Oracle instance to manage and maintain, unlike cluster and MPP configurations.
Far more applications are available that can leverage SMP systems than cluster or MPP configurations.
SMP systems are less expensive than NUMA, clusters, or MPP configurations in similar CPU configurations because memory and I/O subsystems are not duplicated to the same degree.
This is not to say that clusters or MPP systems are not a valid approach. Certainly, if scalability demands exceed the capabilities of SMP machines, clusters or MPP systems may provide the only viable solution. However, companies have ...