Abstract: In a mass storage system having a multiplicity of storage volumes containing addressable data, the assignment of newly received data sets to the best storage volume is accomplished by determining the best match of the data set to the available volumes. Such selection enables maximum storage use of each volume. The best volume is one that provides memory space efficiency for the job at hand, and considers the volume life expectancy, the numbers of users, the shareability of the volume, and the status of the volume. First, all eligible volumes are listed. Then these volumes are sorted according to each volume's match and risk factors to the data set to be stored. The best fitting volumes are selected first for the actual data transfer and storage operation.