Method and apparatus for providing continuous access to shared tape drives from multiple virtual tape servers within a data storage system

摘要

A method for providing continuous access to shared tape drives from two virtual tape server (VTS) nodes is disclosed. A group of tape drives are connected to two VTS nodes via a set of switches. Both VTS nodes can concurrently process requests to mount physical tape cartridges to separate tape drives. The selection of a tape drive to fulfill a volume mount request on a physical volume begins by locking down any access to a tape drive table having a composite view of all the tape drives shared between the two VTS nodes. An available tape drive is then selected to mount the physical volume, and an entry in the tape drive table is updated to claim ownership of the tape drive. A reservation command is sent to the tape drive to lock down any access to the tape drive, and the lock to the tape drive table is released. Having claimed ownership to the tape drive, the VTS node can now perform the volume mount request.