High Availability

The ChorusOS operating system incorporates several features that provide high availability services, including:

• Black Box

• Dynamic Reconfiguration

• Memory Protection

• Watchdog timer

Black Box

The black box feature provides an enhanced mechanism for tracing the activity of the system, so that the exact cause of any failure can be determined quickly and easily.

Black box timer is elaborated further in "Black Box (BLACKBOX)".

Dynamic Reconfiguration

The dynamic process management feature of the ChorusOS operating system allows processes to be loaded dynamically, from either disk or the network, without first halting the system. This provides the basis for a dynamic reconfiguration capability that minimizes service downtime, and keeps existing services available while the system is modified or upgraded. Dynamic reconfiguration also relies on the IPC facilities of the ChorusOS operating system to transfer inbound communication to the new processes transparently.

For example, with the ChorusOS operating system running in a Private Branch Exchange (PBX), features such as call forwarding (or follow me) can be added without interrupting the basic telephone service and without reconfiguring the entire telephone network.

Memory Protection

Different applications can run in different memory address spaces, which are protected from one another. If one application fails, it can corrupt only its own data but cannot corrupt the data of other applications, or of the system itself. This mechanism confines errors and prevents their propagation.

Memory Protection is elaborated further in "Protected Memory (MEM_PROTECTED)".

Watchdog Timer Protection

The watchdog timer feature provides a two-tier watchdog mechanism to monitor hardware and the operating system by checking periodically that they are operating correctly. The application may also be monitored if it uses the debug-aware watchdog timer API.

Watchdog timer is elaborated further in "Watchdog Timer (WDT)".