Abstract: A multi-session data storage facility coordinates similar status changes across all sessions at appropriate times. In each session, a data mover implements data mirroring by copying updates from the primary storage to the secondary storage. A master data set, accessible by all sessions, includes a common area for posting commands and/or errors to all sessions and individual session areas for posting errors occurring in particular sessions. When a data mover receives a host initiated command, this data mover becomes a “master.” Initially, the master data mover lists the command in the master data set's common area. Whenever other, “slave” data movers notice a command in the master data set's common area, they respond by suspending their formation of consistency groups and responding with a “ready” message. The “ready” message comprises the slave data mover's consistency form time (i.e.

Abstract: A data storage library utilizes library-local features to regulate access to shared read/write drives among multiple hosts, and thereby avoid the need for arbitrating host software. The library includes multiple data storage media, multiple data storage media slots, multiple read/write drives, and a library controller. The slots are originally partitioned into multiple logical libraries. Normally, the library shares the read/write drives among all hosts. However, when a host submits a request to unload a cartridge from a read/write drive, the library only honors that request if the host has access rights to the logical library from where the cartridge was originally loaded. Similarly, for each slot, the controller prevents a requesting host from loading a cartridge from that storage slot unless the requesting host has access rights to the logical library that includes that storage slot.