In the present work we study the transient behavior of some two-state
bulk queueing models with (i) Intermittently available server, i.e. the
server goes either for rest or to attend some very urgent jobs when the
queue length is greater than or equal to zero. The server has the option
to start a fresh service instantaneously or to make interruption, but it
is assumed that he completes the service in hand before the
interruption, (ii) Multiple vacations, i.e. the server begins a vacation
with probability 'one' each time the system becomes empty. If the server
returns from a vacation to find the system not empty. If the server
returns from a vacation to find no customers waiting, it begins another
vacation immediately, and continues in this manner until it finds at
least one customer waiting upon returning from a vacation (multiple
vacations), and (iii) Non- exhaustive service, i.e. the server may go on
vacation even if there are some customers waiting for service or
vacations may start even when customers are present in the system.