text: With rapid development of technology, computers, such as desk-top computers and notebook computers, are essential for enterprises and individuals. In addition, with the development of the communication technology, E-commerce (electronic commerce) has become more widespread. However, personal computers do not have enough abilities to satisfy the requirements of transnational business activities, and thus a variety of servers are developed for businesses.
  In a restricted height of the server rack, developers would stack the most possible amount of servers in the server rack in order to enhance the overall performance of the servers. To achieve convenient maintenance of the servers, the servers are drawably disposed in the server rack. To prevent the electronic components from interfering with each other during the insertion or the drawing out of the servers, the servers are usually spaced apart in a distance according to the most protruding electronic component thereon.