Patent ID: 8392370

Claim:
A method for use in managing data on data storage systems, the method comprising: defining first rules for candidate data unit selection, wherein the first rules are based on characteristics of data units, wherein the characteristics of the data units include age of each data unit, last access time for each data unit, size of each data unit, and file type of each data unit; automatically executing the first rules on a primary data storage system to examine the data units on the primary data storage system, wherein the first rules identify the data units for migration; based on the first rules, dividing the data units on the primary data storage system into priority groups, wherein the priority groups are based on usage information of the data units; identifying a priority group for migration; migrating each data unit of the identified priority group from the primary storage system to a secondary storage system, wherein each data unit is migrated to the secondary storage system within the same storage domain; creating an association between the primary storage system and the secondary storage system for maintaining a consistency group for the data units; replacing each migrated data unit with metadata on the primary storage system, wherein the metadata has a same identifier as the migrated data unit the metadata is replacing and stores priority data associated with the migrated data unit the metadata is replacing; freeing up data storage space in the primary storage system corresponding to each data unit of the identified priority group; based on second rules, determining whether an access attempt for one of the migrated data units can be satisfied from the secondary storage system, wherein the second rules indicate how to access the one of the migrated data units based on the determination, completing the access attempt by accessing the one of the migrated data units from the secondary storage system; determining whether the access attempt causes the one of the migrated data units to belong to a different priority group by changing usage information of the one of the migrated data units; and based on the determination, copying a subset of contents of the one of the migrated data units from the secondary storage system to the primary storage system after the access attempt has been satisfied from the secondary storage system.