The use of data and its frequency of use changes over time. This can be roughly divided into "frequently accessed data" and "infrequently accessed data". Data having a high frequency profile will require to be fetched immediately and should be stored on high-performance storage devices. However, storing infrequently accessed data on high-performance storage devices generates unnecessary cost. To meet the growing demand for cost-effective high-capacity storage, for less frequently accessed data, Fujitsu provides high-capacity, highly-reliability, yet low-cost, Nearline disk drive options in its ETERNUS disk storage systems.