Method for calculating tier relocation cost and storage system using the same

A method for calculating a tier relocation cost of a storage system composed of a storage device coupled to one or more upper level devices and a management terminal;

• the storage device comprising
• a plurality of memory device units assigned to different tiers respectively,
• a data location management unit configured to manage location of data in the respective tiers and migration of data among the tiers, and
• a migration amount calculation unit configured to calculate calculating a data storage time in the respective tiers and a data migration amount when data are migrated among the tiers;
• the management terminal comprising an input unit, an output unit, and a cost calculation unit;
• the method comprising:
• based on a result calculated using the migration amount calculation unit, calculating, using the cost calculation unit:
• (1) a stored cost for storing data in a tier;
• (2) a first migration cost for migrating data to an upper tier level;
• and
• (3) a second migration cost for migrating data to a lower tier level;
• and
• displaying at least one of the calculated costs (1) through (3) is displayed on the output unit of the management terminals
• wherein the method further comprising:
• calculating the second migration cost using at least a migration data amount, a migration destination tier level and a migration source tier level;
• and
• performing the calculation so that an amount of increase in the second migration cost does not exceed an amount of decrease in the stored cost.