NonStop Systems Introduction for H-Series RVUs

Integrity NonStop NS-Series Server Architecture

NonStop Systems Introduction for H-Series RVUs—540083-001

7-15

Cost-Effective System Expansion

You have seen that the architecture of Integrity NonStop servers provides continuous

availability for applications. The replication of hardware components throughout the

system and the implementation of system and user processes as process pairs

achieve a high degree of fault tolerance for the NonStop application environment.

However, application fault tolerance is not the only benefit conferred by the Integrity

NonStop server architecture. The unique value of Integrity NonStop servers lies also in

their easy expandability in reasonable cost increments. To support the unpredictable

growth of your applications, you can add as many processors as you need at any given

time, up to a maximum of 16 processors in one system. If you need even more power,

you can join systems in an Expand network. For example, two 16-processor systems

connected through Expand software give the power of 32 processors.

Parallel Processing for High Performance

Multiple processors improve performance because the system can distribute

transactions across the processors. The processors then execute the transactions in

parallel. In addition, individual transactions can often be divided into smaller units of

work, which can then be distributed across multiple parallel processors. Because the

processors do not share any resources, the system benefits from the full power of the

added processors. For example, a dual-processor system yields twice the power of a

single processor, a three-processor system yields three times the power of a single

processor, and so on.

By contrast, adding another processor in a shared-memory configuration does not

result in a commensurate increase in processing power because all the processors are

contending for the same memory resources.

Figure 7-9 on page 7-16 shows that the performance of an Integrity NonStop server

tends to increase at a linear rate as more processors are added.