Carousels are rotatable closed-loop storage systems for small items. We consider the multi-carousel system in which a S/R machine serves more than one carousel through a transfer device called traverser. The S/R machine is placed on the traverser and can be transferred to adjacent carousels. Since the cost of a traverser is estimated approximately to be a half of that of a S/R machine, the utilization of multi-carousel system is an effective way in reducing initial installation cost for a great number of manufacturing firms if the pallet demands are relatively low. In order to estimate the cost and performance accurately, analytic models of expected cycle time for single command and dual command operations. performance evaluations are fulfilled based on the expected cycle time models for each command operations.