Availability Guide for Problem Management

Auditing Systems for Fault Tolerance
Availability Guide for Problem Management–125509
7-2
Continuous Operations
How Tandem Systems Achieve Fault Tolerance
Tandem systems achieve fault tolerance by providing the following configurations:
•
Process pairs for user processes and system processes
•
Data transfers over separate and independent paths
•
Independent multiple processors
•
Dual-bus data paths
•
Dual-port device controllers
•
Dual-port disk drives
•
Mirrored disk drives
•
Multiple power sources
•
Client/server fault-tolerant configurations
The Introduction to Tandem NonStop Systems and the Guardian Programmer’s Guide
provide more information about these configurations.
Figure 7-1. Continuous Operation of a NonStop System
CDT 029
Backup
Process
Checkpoint
Messages
Duplicate
Disk Volumes
Primary
Process