An inventory system with two heterogeneous servers and orbital search for feedback customers

This model deals a continuous review (s, S) inventory system with two heterogeneous servers (server-1 and server-2). Server-1 serves for primary and feedback customers. The primary customers arrival according to a MAP. Service time for both servers, lead time and feedback customers service have exponential distribution. The Primary customers, who finds either two servers are busy or no item is in stock, waits in the finite waiting hall. If the waiting hall is full, then the arriving customer consider to be lost. After the completion of service, the primary customer will decide either to join the orbit (infinite size) for additional service or leaves the system according to a Bernoulli trial. These orbiting customers compete for their service according to a constant retrial policy. Orbital search for server-2 follows a Bernoulli trial. The results are illustrated numerically.