This paper analyses the reliability of a cold standby system consisting of two repairable units and a server. At any time, one of the two units is operating while the other is on cold standby. The server takes some time to visit the system to do preventive maintenance and repair of the system. The preventive maintenance of the system is done by the server after a maximum operation time. The unit fails directly from the normal mode. The failure time of the unit follows negative exponential distribution while the distribution of preventive maintenance and repair times are taken as arbitrary. Repair and maintenance are perfect. The semi-Markov process and regenerative point technique is used to obtain expressions for various measures of system effectiveness. The behaviour of some important reliability measures has been observed graphically giving particular values to various costs and parameters.