Storage subsystem and performance tuning method

1. A storage system comprising a first storage system and a second storage system, the first storage system, which is coupled to a computer and the second storage system, comprising a first storage control device and a plurality of first storage units, the second storage system comprising a plurality of second storage units, wherein the first storage control device:

provides the computer with a logical unit assigned to at least one of the second storage units;

receives a first access request from the computer to the logical unit and sends a second access request to one of plurality of the second storage units according to a relation between the plurality of the second storage units and the logical unit assigned to at least one of the second storage units,

obtains performance information relating to the second access request,

moves data stored in at least one of the plurality of second storage units to at least one of the first storage units according to the performance information, and

changes the assignment of at least one of the second storage units to a logical unit of at least one of the first storage units.

2. A storage system according to claim 1 , wherein the first storage control device moves the data in a unit data with fixed-length, wherein a logical unit has a plurality of the fixed-length data.

3. A storage system according to claim 1 , wherein the first storage system is a file server and the first storage control device moves data in a unit of a file.

4. A storage system according to claim 3 , wherein the performance information includes file reference frequency and/or a time from the last reference.

5. A storage system according to claim 1 , wherein in obtaining performance information by the storage control device, the storage control device measures a response time of the second access request and calculates performance based upon the response time.

6. A first storage system being coupled to a computer and a second storage system, the second storage system having a plurality of second storage units, the first storage system comprising:

a first storage control device; and

a plurality of first storage units,

wherein the first storage control device:

provides the computer with a logical unit assigned to at least one of the second storage units;

receives a first access request from the computer to the logical unit and sends a second access request to one of plurality of the second storage units according to a relation between the plurality of the second storage units and the logical unit assigned to at least one of the second storage units,

obtains performance information relating to the second access request,

moves data stored in at least one of the plurality of second storage units to at least one of the first storage units according to the performance information, and

changes the assignment of at least one of the second storage units to a logical unit of at least one of the first storage units.

7. A first storage system according to claim 6 , wherein the first storage control device moves the data in a unit data with fixed-length, wherein a logical unit has a plurality of the fixed-length data.

8. A first storage system according to claim 6 , wherein the first storage system is a file server and the first storage control device moves data in a unit of a file.

9. A first storage system according to claim 8 , wherein the performance information includes file reference frequency and/or a time from the last reference.

10. A first storage system according to claim 6 , wherein in obtaining performance information by the storage control device, the storage control device measures a response time of the second access request and calculates performance based upon the response time.