Providing Open Architecture High Availability Solutions

interpreters, where a given interpreter provides a collection of abstract objects to an interpreter

above it. For example, a collection of hardware components that comprise a computer motherboard

interprets the application that is hosted on it. The interprets view is depicted in Figure 6.

In Figure 6, the components have been stratified to show their interpretive relationships.

Components C6 and C7 might represent hardware components, and C2 and C5 might represent

operating system components, for example. This view will be used in the following section to help

derive failure rates of systems modeled this way.

Section 5.0 uses these concepts when defining a system model. The system model is a computer-

usable representation of the capabilities, characteristics and dependencies of all of the components

that could be included in a system.

3.4.2 System Models without Service Restoration

In this section, the reliability of systems without service restoration is examined. This will provide

an understanding of reliability in the absence of fault recovery, providing for example, the mean

time-to-failure for a collection of interacting components. Here, relevant summarized citations are

made from [Lyu96].

The simplest approximation of a system’s failure rate, λ, can be shown to be:

Figure 6. The Interpretive Interface

C6 C7

interpreter i

interpreter i+1

interpreter i+2

interpreter i+3