Moving cartridge between library strings

A method for determining a relay-point library string when a library manager moves a particular cartridge (specific cartridge) to an empty drive (target drive) for mounting, the method comprising:

• (a) receiving a command from an application to mount a specific cartridge in a library string located on one side of the relay-point library string;
• (b) searching for the target drive for mounting the specific cartridge among the plurality of library strings LS, and finding the target drive in a library string on an other side of an interposed relay-point library string relative to the library string in which the specific cartridge is located;
• (c) selecting a relay-point library string of a plurality of relay-point library strings LS on the basis of predetermined conditions to move the specific cartridge using at least two shuttle connections SC to the found target drive;
• and
• (d) searching to determine whether or not there is a newly available drive in the relay-point library string other than the selected relay-point library string before the selected cartridge reaches the selected relay-point library string (selected relay-point LS).