Device initialization of subsystems of a data storage library determines whether a subsystem is homogeneous, having common types of devices; or is heterogeneous, having mixed types of devices. Host names are provided for a subsystem in a predetermined format by concatenating the library name, the subsystem name, and a supplemental character; where the supplemental character is a non-defining character for a homogeneous subsystem. For naming purposes, a heterogeneous mixed device subsystem is partitioned into partitions of devices having common types of devices, each partition characterized as a separate homogeneous subsystem with a host name implementing the supplemental character as a defining character.