Patent ID: 6502165
Filing Date: 2002-12-31
Classification: G06F

Abstract:
A method for accessing identifiable data volumes from a plurality of data storage libraries in response to recall requests, said data storage libraries storing and accessing redundant copies of said identifiable data volumes, said data storage libraries having at least two access levels of storage for storing said identifiable data volumes, said access levels comprising differing access speeds to said stored identifiable data volumes, each said data storage library migrating data volumes from faster said access levels of said storage to slower said access levels of said storage, said identifiable data volumes each directly associated with a token, said token providing an indicator of said access level of said identifiable data volume in said data storage library, said recall requests additionally requesting said directly associated tokens, said method comprising the steps of:each said data storage library providing current idle time status of said library; in response to said recall request for one of said identifiable data volumes, reading said token directly associated with said data volume from at least two of said plurality of data storage libraries; determining from said read tokens whether a plurality of said directly associated redundant copies of said data volume are at the same said access level and none of said copies of said data volume is at a faster said access level, such that said copies of said data volume are stored in said data storage libraries at the same fastest available said access level; upon said determining step indicating that at least two of said directly associated redundant copies of said data volume stored in said data storage libraries are at said same fastest available access level, comparing said provided idle time status of said data storage libraries storing said directly associated redundant copies; indicating which of said directly associated data storage libraries provided the greater said provided idle time status; and responding to said idle time indicating step, accessing said data volume from said indicated data storage library.