Storage apparatus, patrolling method and storage system

A patrolling method comprising:

• providing a written state bit map memory that stores a written state bit map that includes bits each allocated to one of partial areas of a storage device for storing write management information indicating whether written data is present in a partial area of the storage device that is allocated to one of the bits;
• providing a patrol object bit map memory that stores a patrol object bit map includes bits each allocated to one of the partial areas of the storage device for storing patrol object information indicating whether each of the partial areas allocated to the bit is a patrol object;
• setting a value indicating that data is written into a partial area of the storage device to a bit allocated to the partial area of the storage device in which the data is written, upon data being written into the partial area of the storage device in response to a write request from a host apparatus;
• copying the write management information to the patrol object information prior to an execution of a patrolling process;
• setting a value indicating the patrol object to a second bit of three successive bits stored in the patrol object bit map memory, in the case that a value indicating the patrol object is stored to a first bit of the three successive bits, a value not indicating the patrol object is set to the second bit of the three successive bits, and a value indicating the patrol object bit map memory is set to a third bit of the three successive bits, and
• performing the patrolling process on the partial areas of the storage device corresponding to a bit of the patrol object bit map memory that stores the patrol information indicating the patrol object.

A storage system comprising:

• a host apparatus that sends requests for writing data and reading data;
• and
• a storage apparatus that writes data into a storage device or reads data out from the storage device in response to a request received from the host apparatus, the storage apparatus including
• a written state bit map memory that stores a written state bit map that includes bits each allocated to one of partial areas of the storage device for storing write management information indicating whether written data is present in a partial area of the storage device that is allocated to one of the bits;
• a bit map management section, when data is written into a partial area of the storage device in response to a write request from the host apparatus, that sets a value indicating that the data is written into the partial area to a bit allocated to the partial area in which the data is written;
• a patrolling process section for performing a patrolling process on the partial areas of the storage device on the basis of the write management information stored in the written state bit map memory;
• and
• a patrol object bit map memory that stores a patrol object bit map includes bits each allocated to one of the partial areas for storing patrol object information indicating whether partial areas allocated to the bit is a patrol object,
• wherein the bit map management section copies the write management information to the patrol object information prior to an execution of a patrolling process, and the patrolling process section performs the patrolling process on the partial area of the storage device corresponding to a bit of the patrol object bit map memory that stores the patrol information indicating the patrol object,
• wherein the bit map management section set a value indicating the patrol object to a second bit of three successive bits stored in the patrol object bit map memory, in the case that a value indicating the patrol object is stored to a first bit of the three successive bits, a value not indicating the patrol object is set to the second bit of the three successive bits, and a value indicating the patrol object bit map memory is set to a third bit of the three successive bits.