Storage system

A storage system, comprising:

• a redundancy group formed of a plurality of storage drives configured to store host data and redundant data in a distributed manner;
• and
• a controller configured to control access to the redundancy group,
• the controller being configured to:
• select, from among the plurality of storage drives in the redundancy group, a part of the plurality of storage drives in an upper limit number equal to or smaller than a redundancy level of the redundancy group, and set the part of the plurality of storage drives to a power saving state;
• acquire, from the part of the plurality of storage drives, a pair including a first value and a second value;
• select, from the part of the plurality of storage drives, a storage drive based on the pair meeting a rule;
• receive, from a host, a read request with respect to a target storage drive included in the redundancy group;
• and
• restore, when the target storage drive is in the power saving state, target data corresponding to the read request from data collected from a part of the plurality of storage drives different from the target storage drive in the redundancy group, and return the target data to the host,
• wherein the pair denotes a location based on the first value and the second value.