A data storage library and method of operation are disclosed wherein access at least to part of at least one robotic mechanism from the data storage library's exterior is permitted. Access is accomplished through a service port in the library's housing. Access to the storage cells, and thus the data cartridges sitting therein, from the library's exterior is blocked. Blocking access to the storage cells may be provided by a geometry of the service port itself, or by a combination of a door and the robotic mechanism being serviced filling the opening created by the service port. For robotic mechanisms operating on a track, part of the track may be routed through the service port to bring the robotic mechanisms to the exterior of the library for maintenance purposes.