Patent ID: 8001339

Claim:
For use in a virtual data storage system for use with a client system and a plurality of physical storage devices, the virtual data storage system including a device emulator for receiving commands and data from the client system and a storage system for storing the data as data objects to the plurality of physical storage devices in accordance with storage management policies, a method of managing multiple copies of stored data objects on multiple media types over time, the method comprising: establishing a plurality of storage pools, each storage pool defining a group of physical storage devices that are to be treated in a uniform manner, the plurality of storage pools including a disk pool composed of a plurality of storage disks and including a tape pool composed of a plurality of storage tapes; establishing a policy composed of a series of policy copy/delete rules that directs movement of data objects into the storage pools, wherein each rule defines a destination storage pool, a length of time that the data objects are to remain in the destination storage pool, and a data source for the data objects; and performing copy and delete actions to manage copies of data objects among the storage pools in accordance with the policy; wherein the series of policy copy/delete rules includes: (i) a first rule that has the disk pool as the destination storage pool, a limited retention time as the length of time that the data objects are to remain in the destination storage pool, and an external source as the data source; (ii) a second rule that has the tape pool as the destination storage pool, an unlimited retention time as the length of time that the data objects are to remain in the destination storage pool, and the disk pool as the data source; wherein the copy action in accordance with the second rule is performed as late as possible but prior to the delete action in accordance with the first rule.