Computer system and storage management method

A storage management method for a computer system comprising a storage system and a management computer configured to manage the storage system:

• wherein the storage system comprises:
• a plurality of storage medias providing storage areas which are managed as a plurality of tiers each of which with different I/O performance;
• and
• a control unit configured to allocate the storage area from the storage tier to a volume to store data indicated by a write request from a host,
• wherein the management computer comprises a control unit,
• wherein the storage management unit comprises the following steps executed by the control unit:
• obtaining storage media information managing information of structure and I/O performance of the storage medias, and I/O performance information of data stored or to be stored in the plurality of storage medias,
• identifying a storage area of storage media with the lowest I/O performance from among the storage areas with higher I/O performance than the obtained I/O performance of the data, on a basis of the obtained storage media information, and
• issuing an instruction to the storage system to create the storage tiers by using the identified storage area of the storage media.