shared memory multi-processors

[Aristo]

I have a question regarding shared memory multi-processors. Why would one want to put a large number of CPUs on a single bus? Why not just multiple (or faster) computers?

Thanks.

[Jeffbx]

For extremely processor-heavy applications:

Large database servers
Image rendering
High volume user validation

- You save tons on software. At the high end of the server line, your software cost can exceed your hardware cost by many times. A single Oralce license can run easily into 6 figures.
- In a data center situation, another important consideration is rack space. The more rack space you use, the more it costs.
- It's one more system to maintain and back up.
- Duplicating drive storage on multiple machines
- Not a trivial thing to load balance across multiple machines

So, it all depends on the application, but there are many instances where multiple processors make more sense than multiple machines (and vice versa).