Storage system including a memory controller that enables each storage controller of a plurality of storage controllers to exclusively read and write control information of the memory

1. A storage system comprising:

a plurality of storage controllers; and

a drive box that includes one or more non-volatile storage devices, wherein the drive box includes:

a memory on which reading and writing are performed in a unit different from a unit for reading and writing from/to the one or more non-volatile storage devices, and which stores control information to be used by the plurality of storage controllers; and

a memory controller that enables each storage controller of the plurality of storage controllers to exclusively read and write the control information of the memory by mediating access to the memory from each of the plurality of storage controllers,

the storage system further comprising:

a plurality of memories including the memory; and

a plurality of memory controllers including the memory controller, wherein

each memory of the plurality of memories is connected to only one memory controller of the plurality of memory controllers,

a first memory controller of the memory controllers transmits the information stored in the memory connected to the first memory controller to one or more other memory controllers, and

each of the one or more other memory controllers stores the information received from the first memory controller in the memory connected to each of the one or more other memory controllers.

2. The storage system according to claim 1 , wherein

the drive box includes a battery that supplies a power when external power feeding is stopped, and

the memory retains contents of the memory by the power from the battery when the external power feeding is stopped.

3. The storage system according to claim 2 , wherein

the plurality of storage controllers stops operations when the external power feeding is stopped, and resumes the operations by using the control information stored in the memory when the external power feeding is restored.

4. The storage system according to claim 1 , wherein

the memory controller writes contents of the memory to the one or more non-volatile storage devices or another backup storage device within the drive box when external power feeding is stopped.

5. The storage system according to claim 1 , wherein the memory includes a non-volatile memory element.

6. The storage system according to claim 1 , wherein

the first memory controller stores the information received from one storage controller of the plurality of storage controllers in the memory connected to the first memory controller according to an instruction from the one storage controller, and transmits the information received from the one storage controller to the one or more other memory controllers,

each of the one or more other memory controllers transmits a write completion notification indicating that the writing of the information received from the first memory controller into the memory connected to each of the one or more other memory controllers is completed to the first memory controller, and

the first memory controller notifies the one storage controller of a write completion of the information received from the one storage controller when the write completion notification is received from all the one or more other memory controllers.

7. The storage system according to claim 1 , wherein

the drive box includes a device protocol conversion unit, and

each of the plurality of storage controllers transmits a command for the memory and a command for the one or more non-volatile storage devices according to an access protocol for accessing the memory, and

the device protocol conversion unit converts the command for the one or more non-volatile storage devices into a command of an access protocol for accessing the one or more non-volatile storage devices.

8. The storage system according to claim 1 , wherein the drive box includes a controller protocol conversion unit,

each of the plurality of storage controllers transmits a command for the memory and a command for the one or more non-volatile storage devices according to an access protocol capable of being converted into both an access protocol for accessing the memory and an access protocol for accessing the one or more non-volatile storage devices, and

the controller protocol conversion unit converts the command for the memory into a command of the access protocol for accessing the memory, and converts the command for the one or more non-volatile storage devices into a command of the access protocol for accessing the one or more non-volatile storage devices.

9. A control method of a storage system, wherein the storage system includes

a plurality of storage controllers, and

a drive box that includes one or more non-volatile storage devices, and a memory on which reading and writing are performed in a unit different from a unit for reading and writing from/to the one or more non-volatile storage devices and which stores control information to be used by the plurality of storage controllers, and

the control method comprising the steps of:

receiving an exclusive access command for the control information of the memory from one storage controller of the plurality of storage controllers;

letting another access command received from storage controller different from the one storage controller wait until the exclusive access command is completed;

executing the other access command after the exclusive access command is completed;

writing contents of the memory to the one or more non-volatile storage devices or another backup non-volatile storage device within the drive box when external power feeding is stopped;

waiting, by the plurality of storage controllers, for a restoration completion notification from the drive box when the external power feeding is restored after the external power feeding is stopped;

re-storing, by the drive box, the contents of the memory written in the one or more non-volatile storage devices or another backup non-volatile storage device into the memory;

transmitting, by the drive box, the restoration completion notification indicating that the contents of the memory are re-stored in the memory to each of the plurality of storage controllers; and

resuming, by each of the plurality of storage controllers, an operation when the restoration completion notification is received.

10. The control method according to claim 9 , wherein the drive box includes a memory controller,

each of the plurality of storage controllers includes a processor that performs control and a processor memory connected to the processor,

the control method further includes

transmitting, by the processor of the one storage controller of the plurality of storage controllers, information stored in the processor memory of the one storage controller to the memory controller,

storing, by the memory controller, the transmitted information in the memory of the drive box,

transmitting, by the memory controller, updated information to the processor of the one storage controller when the information stored in the memory is updated by another processor different from the processor of the one storage controller, and

reflecting, by the processor of the one storage controller, the updated information to the information stored in the processor memory of the one storage controller.

11. A control method of a storage system, wherein

the storage system includes

a plurality of storage controllers, and

a drive box that includes one or more non-volatile storage devices, and a memory on which reading and writing are performed in a unit different from a unit for reading and writing from/to the one or more non-volatile storage devices and which stores control information to be used by the plurality of storage controllers, and

the control method comprising the steps of:

receiving an exclusive access command for the control information of the memory from one storage controller of the plurality of storage controllers;

letting another access command received from a storage controller different from the one storage controller wait until the exclusive access command is completed;

executing the other access command after the exclusive access command is completed, wherein

the drive box includes a plurality of memories including the memory, and

the control method further comprises:

writing information stored in one of the plurality of memories into the other one or more memories.

12. The control method according to claim 11 , further comprising:

writing the information stored in one memory of the plurality of memories by the one storage controller of the plurality of storage controllers into the other one or more memories different from the one memory; and

notifying the one storage controller that writing of the information is completed after writing of the information into the other one or more memories is completed.