Patent ID: 7831575

Claim:
A library virtualization module (LVM) comprising: at least first and second bidirectional host input/output, each for connection to a respective associated one of at least first and second hosts; and a bidirectional library input/output, for connection to a library, said library having resources divisible into at least first and second divisions of resources, a processor comprising instruction for causing the LVM to: divide said resources of said library between said at least first and second hosts to allocate a first division of resources to said first host and to allocate a second division of resources to said second host; receive Small Computer Serial Interface (SCSI) commands at said at least first and second bidirectional host input/outputs; receive a first SCSI command at the first bidirectional host input/output, the first SCSI command relating to a resource outside of the first division of resources; modify the first SCSI command to provide a modified SCSI command so that the only resources to which the modified SCSI command relates are said first division of resources of said library; provide said modified SCSI command to said bidirectional library input/output; receive at said bidirectional library input/output library resource information comprising one of: a) address information relating to library resources, b) information quantifying the library resources, and c) address information relating to library resources and information quantifying the library resources, modify said library resource information to provide modified information, and provide the resulting modified information to one of said at least first and second bidirectional host input/outputs; record a unit attention signal received at said bidirectional library input/output following recording of said unit attention signal, receive an access request at said first bidirectional host input/output; supply data representative of said unit attention condition to said first bidirectional host input/outputs in response to receiving said access request at said first bidirectional host input/output, following recording of said unit attention signal receive an access request at said second bidirectional host input/output; supply data representative of said unit attention signal to said second bidirectional host input/output in response to receiving said access request at said second bidirectional host input/output; and delete said unit attention signal subsequent to supplying said data representative of said unit attention signal to both of said first and second bidirectional host input/outputs.