Endurance Software - HP NetServer AA 4000 Administrator's Manual

Chapter 1

Endurance Software

Endurance software integrates and synchronizes processing across four industry-standard
Pentium class systems. All components are capable of multiprocessing, forming a logical, fully
redundant, fault tolerant server. This results in the Windows NT operating system, all
applications, and the local area network logically perceiving the integrated systems in the server
as a standard Windows NT server. Endurance server software provides fault tolerant
functionality, including:
• Redundant processing environment. Using redundant CEs and memory, the software
performs CPU and memory functions in a tightly coupled manner. In the event of a CPU
or memory failure, the operating system remains continuously available, providing
constant computing without any loss of context.
• Redundant I/O subsystem. The software redirects I/O requests from the CE to the IOPs.
The software coordinates all I/O requests, as follows:
- Because all I/O devices in the server physically reside on the IOPs, Software
redirects all I/O requests from the CEs to the IOPs. As a result, these I/O devices are
logically associated with the CE. For example, the software can redirect a CD-ROM
drive physically located in an IOP so that it is logically assigned to the CE (the CE has
complete control of that CD-ROM drive).
- For mirrored disk devices and redundant Ethernet connections, the software
coordinates all I/O processing so that these redundant components appear as a single
logical device. For example, in a mirrored disk set, the two physical disks (one on
each IOP) appear to the CE operating system and applications as one logical disk. If a
disk failure occurs, the disk operations can transparently continue operating without
affecting any server applications or clients.
• Automatic fault detection and reporting. The software continuously monitors the server. If
the software detects a fault, the server isolates the fault and deconfigures any affected
components. When a fault occurs, software ensures that the server remains operational by
automatically using the redundant components. The fault detection and reporting process
occurs seamlessly, and in a fully operational server, it maintains complete server
availability. The software reports all events, including general status, state changes, and
faults, to the Windows NT event log or displays them in windows as they occur.
Introduction
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