Prefetch appliance server

• US 20040117398A1
• Filed: 04/07/2003
• Published: 06/17/2004
• Est. Priority Date: 12/11/2002
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Mogi, Kazuhiko, Nishikawa, Norifumi, Idei, Hideomi, Nomoto, Toyohiro
• Granted Patent: US 7,092,971 B2
• Time in Patent Office: Days
• US Class Current: 707/102
• CPC Class Codes: G06F 12/0862 with prefetch

Abstract

In a system in which a DB is built in a virtualization environment, a management server obtains DB processing information such as a DB processing execution plan and a degree of processing priority from a DBMS, predicts data to be accessed in the near future and the order of such accesses based on the information, instructs to read into caches of storage devices data to be accessed in the near future based on the prediction results, and reads the data that will be accessed in the nearest future into a cache memory within the management server.

Claims

1. A computer that is connected to at least one storage device that stores data of a data base and a data base host that accesses to the data within the data base, the computer comprising:

a first interface section that is connected to the data base host;

a second interface section that is connected to the at least one storage device;

a control unit; and

a cache memory,

wherein the first interface section receives from the data base host an execution plan for a data base management processing to be executed by the data base host,

the control unit preliminarily obtains first identification information indicative of a storage region in the at least one storage device that stores the data to be accessed by the data base host based on the execution plan,

the control unit converts the first identification information into second identification information that is used to indicate the storage region on a network that is connected to the computer and the at least one storage device,

the second interface section transmits a first read request including the second identification information, which requests to read data stored in the storage region,

the second interface section receives data read out from the storage region, and stores the data in the cache memory, and

the first interface section transmits the data stored in the cache memory to the data base host when the first interface section receives an access request including the first identification information from the data base host.

2. A computer according to claim 1, wherein

the first read request includes information that requests to read data stored in the storage region into a cache memory of a storage device having the storage region,

the second interface section further transmits a second read request to read the data read out onto the cache memory of the storage device, and

the second interface section receives the data read out in response to the second read request, and stores the data in the cache memory of the computer.

3. A computer according to claim 1, wherein

the execution plan includes a first identification information that indicates an execution sequence of a plurality of processings to be executed by the data base host, and storage regions that store data for the respective plurality of processings to be used when the plurality of processings are executed, and

the second interface section transmits the first read request to read the data for the respective plurality of processings to be used when executing the respective plurality of processings according to the execution sequence.

4. A computer according to claim 1, further comprising a memory wherein the memory stores correlation between first identification information for identifying storage regions to be accessed that is used when the data base host accesses data stored in the at least one storage device and second identification information that is used by the computer and the at least one storage device to identify storing regions.

5. A computer according to claim 1, wherein the at least one storage device comprises a plurality of storage devices, and the data is distributed across the plurality of storage devices.

7. A computer that is connected to at least one storage device that stores data of a data base and a data base host that accesses to the data within the data base, the computer comprising:

a first interface section that is connected to the data base host;

a second interface section that is connected to the at least one storage device; and

a control unit,

wherein the first interface section receives from the data base host an execution plan for a data base management processing to be executed by the data base host,

the control unit specifies at least one storage region in the at least one storage device that stores data to be accessed by the data base host based on the execution plan,

the control unit converts first identification information included in the execution plan indicating the at least one storage region specified into second identification information that is used by the computer and the at least one storage device to identify the at least one storage region,

the second interface section transmits a read request that requests to read out data stored in the at least one storage region into a cache memory of at least one storage device having the at least one storage region, and

the first interface section transmits, upon receiving an access request including the first identification information from the data base host, the second identification information to the data base host such that the data base host accesses the at least one storage device having the at least one storage region by using the second identification information and reads data from the cache memory of the at least one storage device.

8. A computer according to claim 7, wherein the at least one storage device comprises a plurality of storage devices, and the data is distributed across the plurality of storage devices.

9. A computer according to claim 8, wherein the second identification information indicates a plurality of storage regions distributed across the plurality of storage devices that store the data to be accessed by the data base host.

10. A data prefetching method for a computer that is connected to a host computer that manages a data base and to a storage device that stores data of the data base, including reading data that is to be accessed by the host computer from a storage region within the storage device that stores the data before the host computer issues an access request for accessing the data, the data prefetching method comprising the steps of:

receiving execution plan information for a data base management processing to be executed by the host computer from the host computer;

converting first identification information that is included in the execution plan information and is indicative of a storage region to be accessed along with the data base management processing into second identification information that a storage device having the storage region uses to identify the storage region;

transmitting a read request including the second identification information to the storage device having the storage region to read out data stored in the storage region before receiving an access request for accessing the storage region from the host computer;

receiving data stored in the storage region from the storage device having the storage region, and storing the data in a cache memory of the computer;

receiving from the host computer an access request for accessing the storage region; and

transmitting the data stored in the cache memory to the host computer according to the access request.

11. A data prefetching method according to claim 10, wherein the step of transmitting the read request comprises the steps of:

requesting to read out data stored in the storage region into a cache memory of the storage device; and

requesting to transmit the data stored in the cache memory of the storage device to the computer.

12. A data prefetching method according to claim 10, wherein the execution plan information includes a plurality of first identification information sets indicative of storage regions to be accessed by the host computer, and an access sequence for the host computer to access the storage regions indicated by the plurality of first identification information sets, wherein the step of transmitting the read request includes the step of transmitting a read request including second identification information sets corresponding to the respective plurality of first identification information sets.

13. A data prefetching method for a computer that is connected to a host computer and a storage device that stores data of a data base, including prefetching data that is to be accessed by the host computer from a storage region within the storage device that stores the data, the data prefetching method comprising the steps of:

receiving execution plan information for a data base management processing to be executed by the host computer from the host computer;

converting virtual identification information that is included in the execution plan information and is indicative of a storage region to be accessed by the host computer into physical identification information that is used by a storage device having the storage region to identify the storage region;

transmitting a read request including the physical identification information to the storage device to read out data stored in the storage region into a cache memory of the storage device having the storage region;

receiving from the host computer an access request for accessing the storage region; and

notifying the host computer of the physical identification information according to the access request,

wherein the host computer uses the physical identification information to access the storage device, and reads data from the cache memory.

14. A computer system comprising:

at least one storage device that stores data of a data base;

a host computer that manages the data base; and

a management server that receives from the host computer an access request including virtual identification information for at least one storage region of the at least one storage device, and transfers the access request from the host computer to the at least one storage device having the at least one storage region indicated by the virtual identification information,

wherein the host computer transmits to the management server a processing plan for a data base management processing to be executed by the host computer,

the management server specifies, based on the processing plan, virtual identification information for the at least one storage region that stores data to be used when the host computer executes the data base management processing, converts the virtual identification information into physical identification information indicative of the at least one storage region, and transmits a first request including the physical identification information that requests to read data stored in the at least one storage region before receiving an access request for accessing the data from the host computer,

the at least one storage device transmits the data to the management server,

the management server stores the data received from the at least one storage device in a cache memory of the management server, and transmits the data stored in the cache memory to the host computer when an access request for accessing the data is received from the host computer.

6. A computer according to claim 15, wherein the second identification information indicates a plurality of storage regions distributed across the plurality of storage devices that store the data to be accessed by the data base host.

15. A computer system according to claim 14, wherein the at least one storage device comprises a plurality of storage devices, and the data is distributed across the plurality of storage devices.

16. A computer system according to claim 15, wherein the physical identification information indicates a plurality of storage regions distributed across the plurality of storage devices that store the data to be accessed by the host computer.

17. A computer system according to claim 14, wherein the storage device reads, based on the first request, the data into a cache memory of the storage device,

the management server transmits to the storage device a second request that requests to transmit the data stored in the cache memory of the storage device to the management server, and

the storage device transmits the data to the management server in response to the second request.

18. A computer system according to claim 14, wherein

the management server transmits the first request to the storage device based on an execution sequence for the data base management processing indicated by the processing plan.

19. A computer system comprising:

at least one storage device that stores data of a data base;

a host computer that manages the data base; and

a management server that receives from the host computer an access request including virtual identification information for at least one storage region of the at least one storage device, converts the virtual identification information into physical identification information, and notifies the host computer of the physical identification information,

wherein the host computer transmits to the management server a processing plan for a data base management processing to be executed by the host computer,

the management server specifies, based on the processing plan, virtual identification information for at least one storage region that stores data to be used when the host computer executes the data base management processing, converts the virtual identification information into physical identification information indicative of the at least one storage region, and requests the at least one storage device to read data stored therein into a cache memory thereof before receiving an access request for accessing the data from the host computer,

the management server transmits the physical identification information to the host computer when an access request for accessing the data is received from the host computer, and

the host computer uses the physical identification information to access the data stored in the cache memory of the storage device.

20. A computer system according to claim 19, wherein the at least one storage device comprises a plurality of storage devices, and the data is distributed across the plurality of storage devices.

21. A computer system according to claim 20, wherein the physical identification information indicates a plurality of storage regions distributed across the plurality of storage devices that store the data to be accessed by the host computer.