Disk array device, disk array system and cache control method

A disk array system, comprising:

• a host device;
• and
• a disk array device configured so as to be communicable with the host device that controls duplicate writing to a cache memory carried out by a master controller and a slave controller, wherein
• the master controller is provided with a master I/O unit, a master cache memory and a master cache control unit,
• the slave controller is provided with a slave I/O unit, a slave cache memory, a buffer memory that is caused to function as the cache memory by altering memory attributes, and a slave cache control unit,
• the slave I/O unit stores write data in the buffer memory and transmits the write data and a write request to the master controller responsive to the slave I/O unit receiving the write request and the write data from a host device, the write request to which has been added identifying information indicating that the write data has been stored in the buffer memory,
• the master cache control unit stores the write data in the master cache memory and transmits the write request to which the identifying information has been added to the slave controller in the case of receiving the write request to which the identifying information has been added, along with the write data, and
• the slave cache control unit alters the attributes of the buffer memory where the write data has been stored to cause the buffer memory to function as the cache memory in the case of receiving, from the master controller, the write request to which the identifying information has been added.

A cache control method of a disk array device that controls duplicate writing to a cache memory carried out by a master controller and a slave controller,

• the master controller being provided with a master I/O unit, a master cache memory and a master cache control unit, and
• the slave controller being provided with a slave I/O unit, a slave cache memory, a buffer memory that is caused to function as the cache memory by altering memory attributes, and a slave cache control unit, wherein
• the slave I/O unit executes a step of receiving a write request and write data from a host device, a step of storing the write data in the buffer memory, and a step of transmitting the write data and a write request to the master controller responsive to the slave I/O unit receiving the write request and the write data from a host device, the write request to which has been added identifying information indicating that the write data has been stored in the buffer memory,
• the master cache control unit executes a step of receiving the write request to which the identifying information has been added, along with the write data, a step of storing the write data in the master cache memory, and a step of transmitting the write request to which the identifying information has been added to the slave controller, and
• the slave cache control unit executes a step of receiving, from the master controller, the write request to which the identifying information has been added, and a step of altering the attributes of the buffer memory where the write data has been stored to cause the buffer memory to function as the cache memory.