Abstract: In summary, preferred embodiments disclose a system, method, and program for data transfer commands to perform data transfer operations between a first processing unit and second processing unit. The second processing unit controls access to a storage system. The storage system storage space is logically divided into multiple tracks. Each track includes one or more data records. Each data record includes an index area providing index information on the content of the data record and a user data area including user data. An initialization command is communicated from the first processing unit to the second processing unit indicating a range of tracks on which data transfer operations will be performed. For each track in the range of tracks, a set of data transfer operations is executed. This set of data transfer operations includes transmitting a data transfer command from the first processing unit to the second processing unit.