| 主权项 |
1. A tiered storage system comprising:
a first storage device which comprises a storage area including a plurality of physical chunks having a first size; a second storage device which comprises a storage area including a plurality of physical chunks having the first size, the second storage device having a lower access speed and a larger storage capacity than the first storage device; and a storage controller which controls the first and second storage devices, wherein: the storage controller comprises a logical volume management unit, an access statistics collection controller, an evaluation controller and a relocation controller; the logical volume management unit manages a logical volume including a plurality of logical chunks having the first size, the logical volume being provided to a host computer, the storage areas of the first and second storage devices being allocated to the logical volume physical chunk by physical chunk; the access statistics collection controller collects, during respective monitoring periods, access frequency statistical values representing statuses of accesses to the respective logical chunks; the evaluation controller sets, in access statistical data, a first access frequency statistical value and a second access frequency statistical value associated with a respective one of the logical chunks, the first access frequency statistical value representing a status of access to the respective one of the logical chunks which is in a first location state in which data of the respective one of the logical chunks is located on the first storage device, the second access frequency statistical value representing a status of access to the respective one of the logical chunks which is in a second location state in which data of the respective one of the logical chunks is located on the second storage device; the evaluation controller updates, during the respective monitoring periods, the first or second access frequency statistical value included in the access statistical data and corresponding to a location state of data of the respective one of the logical chunks, based on one of the collected access frequency statistical values, which is associated with the respective one of the logical chunks; and the relocation controller determines whether it is necessary to change the location state of the data of the respective one of the logical chunks, based on the first and second access frequency statistical values of the respective logical chunks. |
