A method for access to a file in a plurality of data storage libraries and data memory library - system

摘要

A data storage library system with a plurality of data storage libraries and at least one director accesses a redundant copy of an identifiable data volume, employing the idle time status of each library to balance the workload. The data volumes may be stored in cache storage and backing storage which have different levels of access speed. A director requests a data volume, and the library controller of each library determines its current idle time status, providing the idle time status to the requesting director when it provides a synchronization token directly associated with the requested data volume. The token indicates the update level and the access level of the data volume in the library. The director, upon determining from the tokens that at least two of the copies of the data volume are at the same fastest available access level, compares the provided idle time status of the libraries storing those copies, and accesses the data volume from the library having the greater idle time status.