High Availability

QNX SDP8.0System ArchitectureDeveloperUser

The term High Availability (HA) is commonly used in telecommunications and other industries to describe a system's ability to remain up and running without interruption for extended periods of time.

The celebrated five nines availability metric refers to the percentage of uptime a system can sustain in a year—99.999% uptime amounts to about five minutes of downtime per year.

Obviously, an effective HA solution involves various hardware and software components that combine to form a stable, working system. Assuming reliable hardware components with sufficient redundancy, how can an OS best remain stable and responsive when a particular component or application program fails? And in cases where redundant hardware may not be an option (e.g., consumer appliances), how can the OS itself support HA?

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