Storage system

A method for controlling a switch device connected to a host, a first storage device, and a second storage device having a cache memory, the method comprising:

• receiving, by the switch device, a copy command indicating to copy target data stored in the first storage device to the second storage device from the host,
• transmitting a reading out command indicating to read out the target data stored in the first storage device corresponding to the copy command to the first storage device,
• receiving the target data corresponding to the transmitted reading out command from the first storage device, and
• transmitting, to the second storage device, a writing command for writing the target data and release information indicating that the target data is releasable from the cache memory.

A system connectable to a host, comprising:

• a switch device;
• a first storage device;
• and
• a second storage device including
• a storage module for storing data, and
• a cache memory for temporarily storing the data to be written into the storage module,
• wherein the switch device executes:
• receiving a copy command indicating to copy target data stored in the first storage device to the second storage device from the host,
• transmitting a reading out command indicating to read out the target data stored in the first storage device corresponding to the copy command to the first storage device,
• receiving the target data corresponding to the transmitted reading out command from the first storage device, and
• transmitting, to the second storage device, a writing command for writing the target data and release information indicating that the target data is releasable from the cache memory,
• wherein the second storage device executes:
• storing the target data to the cache memory,
• storing the target data to the storage module, and releasing the target data stored in the cache memory preferentially from other data stored in the cache memory upon receiving the release information and the target data is stored in the storage module.

A storage device comprising:

• a storage module for storing data;
• a cache memory for temporary storing data to be written into the storage module;
• and
• a processor executing:
• storing the data to the cache memory,
• storing the data to the storage module, and
• releasing the data stored in the cache memory preferentially from other data stored in the cache memory upon receiving release information and the target data is stored in the storage module.