Supervisory Control of a Database Unit

To effectively enhance service availability, this paper proposes a redundancy configuration for a database unit residing in a command and control (C2) system that supports air operations. The results of modeling, supervisory control, and performance analysis of the database unit are presented. The unit is modeled as a closed Markovian queuing network. State variable feedback is used to implement the functions of restoration and routing upon the identification of the failure of one of the database servers in the unit. Several control policies are evaluated in terms of the resulting mean time to unit failure, the steady state availability, the expected response time, and the service overhead of the database unit.