NonStop Systems Introduction

NonStop Server Architecture
NonStop Systems Introduction—527825-001
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Cost-Effective System Expansion
ServerNet clusters allow multiple multiprocessor systems to work together and appear
to client applications as one large processing entity. Up to 24 servers can be joined in
a cluster.
ServerNet clustering provides several benefits, including:
•
Performance. For interprocessor communication, ServerNet clusters take
advantage of the NonStop Kernel message system for low message latencies, low
message processor costs, and high message throughput. The same message
system is used for interprocessor communication within a node and between
cluster nodes. Furthermore, ServerNet clusters take advantage of the
transmission speeds of ServerNet for fast message throughput between nodes.
•
Availability. If a cluster node should experience a problem, the ServerNet cluster
makes it easy to bypass the problem by diverting the workload to other nodes.
•
Manageability. Servernet clusters make it easy to share resources among cluster
nodes. In addition, ServerNet provides a quick-disconnect capability that makes it
easy to implement planned outages.
•
Scalability. ServerNet clusters can be expanded (up to 24 servers) as your
network load increases.
Cost-Effective System Expansion
You have seen that the architecture of 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 very high degree of fault tolerance for the NonStop application environment.
However, application fault tolerance is not the only benefit conferred by the NonStop
server architecture. The unique value of 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.