Patent ID: 7174439

Claim:
A method for managing data stored in a storage unit of a storage apparatus, the storage unit including a first storage medium having a first access speed and a second storage medium having a second access speed, the first access speed being different from the second access speed, the method comprising: determining a first access frequency for information of a first type using an access table maintained by a storage controller of the storage apparatus, the first access frequency being associated with a first period in the past, the storage apparatus being coupled to a remote host system that is configured to access the storage unit of the storage apparatus via a network; determining a second access frequency of the information of the first type using the access table, the second access frequency being associated with a second period in the past, the second access frequency being different than the first access frequency; and transferring at least a portion of the information of the first type from the first storage medium to the second storage medium prior to a second point in time based on the second access frequency determined in the determining-a-second-access-frequency step, the second point in time being associated with the second period in the past, wherein the access table associates a plurality of periods of time for the information of the first type, each period being associated with a number of access requests received for the information of the first type for that period, and wherein the first and second periods are recurring periods.