Restoration of target work in automatic failure- and fault-tolerant multitasking distributed information-control system

Abstract

The paper deals with the organization of target work recovery processes after admissible failures and faults in an automatic failure and fault tolerant multitask distributed multi-machine system of the network structure performing a set of the target functions set by external users. The system is characterized by parallel execution of a set of interacting target tasks performed on separate computer subsystems, which are organized sets of digital computers. The specified level of failure- and fault-tolerance of the task is provided by its replication, i.e. parallel execution of copies of this task on several computers that make up the system, with the exchange of results and the choice of the correct one. The study introduces the characteristics, principles of construction, features of the considered systems and their "philosophical" essence from the point of view of failure- and fault-tolerance. Within the research, we determined the factors of complexity in the design of failure- and fault-tolerant systems of this class. The most general model of malicious computer failure is adopted, in which the computer behavior can be arbitrary, different in relation to other computers interacting with it, and even as malicious. We focus on the part of the problem of organizing dynamic redundancy in the developed system. The problem arises after an acceptable set of faults is detected in this system in some complex (or some set of F complexes) by each of the fault-free digital computers of each such complex and each such fault is also synchronously and consistently identified by place of origin and by type as a software failure of a certain digital computer of this complex. This part of the problem is solved by restoring all necessary information identified in a state of software malfunction of a certain complex. The information is transmitted to this digital computer from fault-free digital computers of this complex. The list of instructions required for such a recovery, as well as the actions of the complex in the recovery process, is determined.