INVESTIGATION OF STRUCTURAL CHARACTERISTICS OF DISTRIBUTED COMPUTING SYSTEMS BASED ON GRAPHS WITH MULTIPLE EDGES OF DIFFERENT TYPES

Abstract

The article considers the issues of fault-tolerant computing systems (CS) development in terms of their structure and redundancy. It is necessary to take into account a great amount of factors, which have an impact on performance, reliability and fault tolerance, during the distributed CS development. For distributed CS such factors contain, among other things, structural characteristics. The dependency graphs of processor nodes (PN)nonfailure operating probability of distributed CS against system structural characteristics are presented in the article. The application of advanced redundancy methods, such as performance redundancy, increases the complexity of structure design problem. In the case of performance redundancy, instead of adding redundant nodes to the system, it is proposed to use redundant computational resources among the involved processor nodes. If a node fails, its tasks are reallocated to a free reserve of nodes, which are able to work. To implement this method of system redundancy, the organization of a multi-program operation mode is required, when some tasks can be performed simultaneously on each node. Need for multi-program operation mode providing leads to increasing the number of system configurations, which have to be analyzed on the design stage and in the case of reconfigurations when a failure takes place. To reduce the labour intensity of a configuration analysis an approach based on graphs with multiple edges of different types is proposed. The use of models based on such graphs makes it possible to represent the structure of CS taking into account a multi-program operation mode and at the same time significantly reduce the computational time of basic characteristics by means of applying relations in the form of a vector, which allows to integrate some relations of different types.