The IBM TotalStorage Enterprise Peer-to-Peer Virtual Tape Server addresses data availability, system availability, remote copy and data vaulting desires for the VTS family. Virtual Tape Controllers exist between MVS hosts and the virtual tape servers to provide replication, transparent tracking, and synchronization of the Logical Tape volumes. The Peer-to-Peer VTS provides multiple copies of all tape data.

The Peer-to-Peer VTS system supports an immediate or deferred copy option. In deferred copy mode, the library schedules creation of the copy upon receiving the rewind/unload command from the host. The copy is then made in the background as VTS activity permits. In immediate copy mode, the copy is started upon receiving the host rewind/unload command and signals completion of the rewind/unload command when the copy operation is complete.

The Peer-to-Peer VTS system appears as one library image to the attached hosts. The single library image is referred to as the composite library. The underlying physical VTS libraries that make up the composite library are referred to as the distributed libraries. All three libraries (the composite library and two distributed libraries) will be defined to the host, whereas the drives and volumes will be defined and associated with the composite library.

The composite library will reflect the overall state of the VTS systems, with individual library status being reflected through the distributed libraries. For example, if one of the distributed libraries is in paused mode and the other is in automated mode, the overall status of the VTS composite library will be automated with messages to the host indicating which of the distributed libraries is paused. If one of the distributed libraries is taken offline at the library, the state of the composite will remain online and operational as long as one of the distributed libraries is operational.