A unified task-based dependability model for hypercube computers

A unified analytical model for computing the task-based dependability (TDB) of hypercube architectures is presented. A hypercube is deemed operational as long as a task can be executed on the system. The technique can compute both reliability and availability for two types of task requirements-I-connected model and subcube model. The I-connected TBD assumes that a connected group of at least I working nodes is required for task execution. The subcube TBD needs at least an m-cube in an n-cube, m⩽ n, for task execution. The dependability is computed by multiplying the probability that x nodes (x⩾I or x⩾2^m) are working in an n-cube at time t by the conditional probability that the hypercube can satisfy any one of the two task requirements from x working nodes. Recursive models are proposed for the two types of task requirements to find the connection probability. The subcube requirement is extended to find multiple subcubes for analyzing multitask dependability. The analytical results are validated through extensive simulation