Data storage library with efficient cartridge eject

Abstract

A data storage library efficiently utilizes I/O slots while maintaining software compatibility by using functional addresses to conduct virtual cartridge moves from storage slots to I/O slots. More particularly, a location-centric library host manages cartridge movement according to functional storage addresses and functional I/O addresses. In reality, the library has multiple cartridge receiving slots, which include physical I/O slots and physical storage slots. In contrast with the physical I/O slots and physical storage slots, functional I/O addresses and functional storage addresses are virtual locations used by the host in managing cartridge locations. Thus, host knowledge of cartridge locations is limited to their functional addresses. The library includes a library map that correlates functional addresses with physical addresses. Initially, an eject command is received from the host. The eject command requests transfer of a cartridge from a source functional storage address to a target functional I/O address. In response to the eject command, irrespective of any physical movement of the cartridge, the library reports successful completion of the requested eject command to the host. The library promptly gives a functional I/O address to the physical storage slot containing the cartridge. When a physical I/O slot becomes available, the library physically moves the cartridge there and either correlates the cartridge's functional I/O address with this physical I/O slot, or registers the cartridge's functional I/O address as empty.