Storage system and method of operating the same

1. A storage system, comprising:

a master storage device configured to store data based on a RAID level determined by a host; a slave storage device configured to store the data according to a command distributed from the master storage device; and

a controller hub configured to couple the slave storage device to the master storage device, wherein the master storage device is further configured to: transfer the command to the slave storage device through the controller hub when the master storage device receives a command processing request from the host; and

transmit a complete queue (CQ) to the host when operations of the master storage device and the slave storage device are completed in response to the command processing request, and

wherein the master storage device is further configured to request a host to allocate a capacity to each function in the master storage device and the slave storage device based on a reference capacity.

2. The storage system of claim 1 , wherein the master storage device is further configured to control the slave storage device such that the data is striped across the slave storage device and the master storage device.

3. The storage system of claim 1 , wherein the master storage device is further configured to control the slave storage device such that the data is mirrored on the slave storage device and the master storage device.

4. The storage system of claim 1 , wherein the master storage device is further configured to generate and store therein a parity for error correction of the data.

5. The storage system of claim 1 , wherein at least one of the master storage device and the slave storage device is further configured to store therein a parity for error correction of the data.

6. The storage system of claim 1 ,

wherein the command processing request includes a read request for reading the data stored in the master and slave storage devices,

wherein the master storage device is further configured to read therefrom one or more pieces of the data corresponding to the read request and to transmit the pieces read from the master storage device to host memory, and

wherein the slave storage device is further configured to read therefrom one or more pieces of the data corresponding to the read request and to transmit the pieces read from the slave storage device to the host memory.

7. The storage system of claim 1 ,

wherein the command processing request includes a write request for storing the data into the master and slave storage devices,

wherein the master storage device is further configured to receive one or more pieces of the data corresponding to the write request from host memory, and to store therein the pieces received from the host memory, and

wherein the slave storage device is further configured to receive one or more pieces of the data corresponding to the write request from the host memory, and to store therein the pieces received from the host memory.

8. The storage system of claim 1 ,

wherein the master storage device is further configured to:

receive, from the slave storage device, pieces of size information indicating capacities of the slave storage device, and

set, as the reference capacity, a greatest common divisor of the capacities of the master storage device and the slave storage device based on the received pieces of size information.

9. The storage system of claim 1 , wherein the master storage device is further configured to determine a number of functions to be allocated to each of the master storage device and the slave storage device based on the reference capacity.

10. The storage system of claim 9 , wherein the master storage device RAID-couples functions, divided according to the number of functions allocated to each of the master storage device and the slave storage device.

11. The storage system of claim 10 , wherein the master storage device is further configured to control the slave storage device to maintain the functions, divided according to the number of functions until the RAID-coupling is initialized.

12. The storage system of claim 9 , wherein the master storage device is further configured to:

output, to the host, allocation information indicating the number of the functions to be allocated to each of the master storage device and the slave storage device, and

transfer, from the host to the slave storage device by a predetermined method, function information allocating the number of functions to the slave storage device.

13. The storage system of claim 12 , wherein, when the slave storage device does not support the predetermined method, the master storage device is further configured to set, as the reference capacity, a capacity of the slave storage device that does not support the predetermined method.

14. The storage system of claim 13 , wherein the master storage device is further configured to:

determine the number of functions to be allocated to each of the master storage device and the slave storage device based on the reference capacity; and

RAID-couple functions, divided according to the number of functions allocated to each of the master storage device and the slave storage device based on the reference capacity.

15. A storage system, comprising: a master storage device configured to store data based on a RAID level determined by a host; a plurality of slave storage devices, each the plurality of slave devices being configured to store the data according to a command distributed from the master storage device; and

a controller hub configured to couple the plurality of slave storages device to the master storage device, wherein the master storage device is further configured to: transfer the command to at least one of the plurality of slave storage devices through the controller hub when the master storage device receives a command processing request from the host; and

transmit a complete queue (CQ) to the host when operations of the master storage device and the at least one of the plurality of slave storage devices are completed in response to the command processing request, and

wherein the master storage device is further configured to request a host to allocate a capacity to each function in the master storage device and the at least one of the plurality of slave storage devices based on a reference capacity.

16. The storage system of claim 15 , wherein the master storage device is further configured to control the plurality of slave storage devices such that the data is striped across the plurality of slave storage devices and the master storage device.

17. The storage system of claim 15 , wherein the master storage device is further configured to control the plurality of slave storage devices such that the data is mirrored on the master storage device and the at least one of the plurality of slave storage devices.

18. The storage system of claim 15 ,

wherein the command processing request includes a read request for reading the data stored in the master storage device and the plurality of slave storage devices,

wherein the master storage device is further configured to read therefrom one or more pieces of the data corresponding to the read request and to transmit the pieces read from the master storage device to host memory, and

wherein the at least one of the plurality of slave storage devices is further configured to read therefrom one or more pieces of the data corresponding to the read request and to transmit the pieces read from the at least one of the plurality of slave storage devices to the host memory.

19. The storage system of claim 15 ,

wherein the command processing request includes a write request for storing the data into the master storage device and the plurality of slave storage devices,

wherein the master storage device is further configured to receive one or more pieces of the data corresponding to the write request from host memory, and to store therein the pieces received from the host memory, and

wherein the at least one of the plurality of slave storage devices is further configured to receive one or more pieces of the data corresponding to the write request from the host memory, and to store therein the pieces received from the host memory.

20. The storage system of claim 15 ,

wherein the master storage device is further configured to:

receive, from the at least one of the plurality of slave storage devices, pieces of size information indicating capacities of the at least one of the plurality of slave storage devices, and

set, as the reference capacity, a greatest common divisor of the capacities of the master storage device and at least one of the plurality of slave storage devices based on the received pieces of size information.