Patent ID: 8429346

Claim:
A method for relocating data in a physical storage pool comprising a plurality of storage tiers having differing performance characteristics, the physical storage pool being mapped into one or more logical units, each logical unit comprising a plurality of logical slices of data storage, the method comprising: receiving a relocation list, the relocation list including, for each of a plurality of logical slices, a slice identifier, a temperature value, and a current physical location; determining a destination tier for each logical slice on the relocation list; evaluating for each logical slice on the relocation list a performance gain expected to be achieved by moving the logical slice from its current physical location to a new location in the destination tier; and relocating data in a logical slice from its current physical location to the new location based on the evaluation; wherein the destination tier comprises a plurality of RAID groups, each RAID group having an expected temperature value and a performance capability value, the performance capability value being proportional to the throughput of the RAID group; and wherein the new location is in a destination RAID group selected based on a ratio of expected temperature value to performance capability value.