NonStop Systems Introduction

The NonStop Kernel
NonStop Systems Introduction—527825-001
6-5
Network Operations
This burden occurs because the networking software requires the computer to focus
on the outside world, while the operating system requires it to focus on local peripheral
devices. Two software systems are working at cross-purposes in the same computer.
By contrast, the NonStop networking environment is a simple extension of the local
operating system. Each node of the network is a computer that was designed for
networking from the outset.
As Figure 6-3 on page 6-5 shows, this computer is already a network composed of
multiple, independent processors and input/output components, all linked by dual
interconnection structures called ServerNet fabrics. In fact, this internal network has
a name: system area network, or SAN. (The ServerNet system area network is
described in Section 7, NonStop Server Architecture.) Processing capacity is easily
expanded by adding more processors to the SAN, and I/O capacity is easily expanded
by adding more I/O components (usually through ServerNet adapters) to the SAN.
Each processor has its own memory, power supply, and backup battery; therefore,
each processor can function independently. However, each processor can also
communicate with all the other processors in the system, as well as with all
input/output components, over the dual ServerNet fabrics.
A separate copy of the operating system runs inside each processor. This distributed
operating system blurs the physical boundaries between processors by making it
Figure 6-3. A NonStop Server as a Network of Processors
Processor 0 Processor 1 Processor 2 Processor 3
ServerNet
adapter
adapter
adapter
Dual ServerNet fabrics
Disks
LAN
ServerNet
ServerNet
VST074.vsd
Planned
processor 4