Storage system and storage control method

Abstract

When a data write request is received from a request source, a storage controller stores write request data in a first volatile storage device, stores a log corresponding to the stored data in a non-volatile storage device, sends a completion response to the request source after storing the log, moves the data stored in the first volatile storage device to a second volatile storage device when no cache hit occurs for the data stored in the first volatile storage device over a first period from a first time when the data is stored in the first volatile storage device, and destages the data stored in the second volatile storage device to the non-volatile storage device when no cache hit occurs for the data stored in the second volatile storage device over a second period from a second time when the data is stored in the second volatile storage device.

Dependencies are inferred from the claim text.