Patent ID: 7334083

Claim:
A library system comprising: a library apparatus storing therein a recording medium as a physical volume, and having a drive unit for accessing to said physical volume; a data processing apparatus processing data recorded on said physical volume in said library apparatus; and a virtual library apparatus interposed between said library apparatus and said data processing apparatus; said virtual library apparatus comprising: a cache holding data read out from said physical volume as a logical volume in order that said data processing apparatus has an access to the data to process the data; a logical drive accessing to said logical volume held in said cache according to an instruction of access for said physical volume in said library apparatus from said data processing apparatus; and a physical layer recording data recorded on said cache as said logical volume by said logical drive on a physical volume in said library apparatus asynchronously with an access to said logical volume by said logical drive; said library system comprising: a collecting means for collecting an access state to said logical volume from said data processing apparatus; a database for retaining said access state collected by said collecting means; and a restoring means determining a restoration priority of said logical volume on the basis of said access state retained in said database, reading out said logical volume from a physical volume retaining said logical volume onto said cache according to said restoration priority, thereby restoring said logical volume to be held in said cache.