“…In several queueing systems when no jobs (i.e., primary job) are available for the server, then the server performs some secondary jobs, this type of model is interpreted as the vacation queueing model, and proposed by Levy and Yechiali [ 20 ]. Later many researchers ([ 9 , 11 , 32 , 15 , 16 ] and the references therein) have been attracted to the queueing models with vacation phenomena, and in this connection, an impressive survey is presented in the survey papers by Doshi [ 8 ] and Ke et al [ 17 ]. For the quality literature on vacation theory, readers are requested to see Takagi [ 29 ] and Tian and Zhang [ 31 ].…”