1.7. Power

1.9. System Clock

A system clock coordinates the activity of the server components . The clock is actually a crystal. When electrical current is applied to the crystal, it vibrates at a constant rate. The number of vibrations is measured in megahertz (MHz).

Each vibration is known as a clock cycle or clock tick . The clock cycles act as a sort of drumbeat that drives the work of all other components. Every action a component makes takes place on a clock tick.

Some components work faster than others, getting their work done in fewer clock cycles. The challenge in server design is to connect all the components in a way that provides a constant data flow through the system but minimizes bottlenecks. The design of the server, combined with the user configuration of the server, determines whether a subsystem works to enhance performance or works as a bottleneck to restrict overall performance.

Data flow in a server can be viewed in a hierarchical, fastest -to-slowest, logical block diagram. Data must move through the system effectively from fast to slow and back. To keep the faster subsystems (processors and memory) working efficiently , the system depends on controllers, memory buffers, parallel buses, and concurrent read and write processes.