A storage management method for use in a storage area network is provided. The storage area network comprises a plurality of host data processors coupled to a virtualization engine, which is coupled to a plurality of physical storage media. Each physical storage media is assigned a tier level. The method comprises storing a threshold storage access value associated with each tier level, presenting virtual disk(s) to a host data processor and receiving I/O requests to the virtual disk from the host data processor. Additionally, metadata is stored which identifies the tier level of the physical storage to which the block corresponds, mappings between the block and blocks of a virtual disk, and an access rate to the data. The access value is periodically compared to at least one threshold rate associated with its tier level. Depending on the result, storage block(s) may be marked for migration to another tier level.