Abstract: The respective physical storage devices of a storage system are set to a power-saving state in which these respective physical storage devices are able to respond to a prescribed type of command. Then, a first prescribed type of command is sent to the respective physical storage devices that are in the power-saving state, and the results of this first prescribed type of command are checked.

Abstract: Proposed is a storage apparatus and its control method capable of performing dynamic load balancing or performance acceleration as a whole by balancing the load to a logical volume. With this storage apparatus, the load status of the volume is measured based on the data volume and command throughput transferred between the higher-level device and the storage unit. In addition, the contents of the volume having a load exceeding the default value are copied to one or more backup volumes based on the measurement results of the load status of the volume, the volume of a copy source and the backup volume of a copy destination are associated with one virtual volume, and the virtual volume is provided to the higher-level device.