Patent ID: 7139782

Claim:
A storage system, which comprises: a first volume connected to receive data from a source volume; a second volume; means for transferring data from said first volume to said second volume; means for suspending transfer of data from said first volume to said second volume in response to instructions to accept test I/O requests; means for servicing, with said second volume, test I/O requests from a secondary host computer to test I/O between said second volume and said secondary host computer during suspension of transfer of data from said first volume to said second volume; and, means for resuming transfer of data from said first volume to said second volume in response to instructions to stop accepting test I/O requests; wherein said means for servicing test I/O requests includes a third volume; wherein said source volume is a primary volume of a primary storage system, said first volume is a front-end volume of a secondary storage system, said second volume is a secondary volume of said secondary storage system, and said third volume is an alternate volume of said secondary storage system.