A communications system may include a plurality of client devices configured to generate client processing jobs, each having a respective unique client ID associated therewith. Another method is provided for a data storage system to consolidate space in one or more logical disks mapped to a virtual volume while the data storage system remains online to a host. The invention is useful in performing surgery on bones, for example, in performing surgery on the knee joint. The second branch extends from one of the first branches. A servo operation is used to set the voltages on the transfer rollers.