Transferring data in virtual tape server, involves determining availability of small chain of data, if large chain is not available while transferring data to physical volumes in peak mode

Disclosed is a system, method, and program for transferring data. Whether data is being transferred to physical volumes in peak mode is identified. If the data is being transferred in peak mode, whether a large chain of data is available for transfer to physical volumes is determined. If the large chain of data is not available, whether a small chain of data is available for transfer to physical volumes is determined. If the small chain of data is available, the small chain of data is transferred to physical volumes. Additionally, if one or more files that have ages greater than a steady state age threshold are available, the one or more files are transferred to the one or more physical volumes. If one or more files that have ages greater than a peak age threshold are available, the one or more files are transferred to the one or more physical volumes.