A service gateway processes a service request received from a host by: relaying the service request from the service gateway to a server over a service session between the service gateway and the server; determining a service request time for the service session; receiving by the service gateway a service response from the server; determining by the service gateway a service response time; calculating by the service gateway a service processing time for the service request from the service request time and the service response time; comparing the service processing time with an expected service processing time; and updating a server busy indicator for the server in response to the comparing. If the service processing time exceeds the expected service processing time, the server busy indicator is updated to indicate that the server is busy. Otherwise, the server busy indicator is updated to indicate that the server is not busy.