COMPUTER SYSTEM, CACHE CONTROL METHOD AND COMPUTER PROGRAM

• US 20140012936A1
• Filed: 07/05/2012
• Published: 01/09/2014
• Est. Priority Date: 07/05/2012
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Aikoh, Kazuhide, Hatasaki, Keisuke
• Granted Patent: US 9,047,195 B2
• Time in Patent Office: Days
• US Class Current: 709/213
• CPC Class Codes: G06F 12/0811 with multilevel cache hierarchies
• CPC Class Codes: G06F 12/0817 using directory methods
• CPC Class Codes: G06F 12/0833 in combination with broadcast means (e.g. for invalidation or updating)
• CPC Class Codes: G06F 12/084 with a shared cache
• CPC Class Codes: G06F 12/0871 Allocation or management of cache space
• CPC Class Codes: G06F 2212/1044 Space efficiency improvement
• CPC Class Codes: G06F 2212/1048 Scalability
• CPC Class Codes: G06F 2212/283 Plural cache memories
• CPC Class Codes: G06F 2212/62 Details of cache specific to multiprocessor cache arrangements
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers

Abstract

The first application program and/or the second application program send(s) an access request to the second cache management module. The second cache management module receives the access request from the first application program and/or the second application program, and references the second cache management table to identify the storage location of the access-target data conforming to the access request. When access-target data exists in first cache area, the second cache management module sends a data transfer request to the first cache management module storing the access-target data, and where access-target data does not exist in the first cache area, acquires the access-target data from the second storage device. When the access-target data is in first cache area, the first cache management module acquires the access-target data conforming to the data transfer request from the relevant first cache area, and sends access-target data to the second cache management module.

Claims

1. A computer system, comprising:

multiple first computers; and

a second computer comprising a second storage device,

wherein each of the multiple first computers comprises a first application program, a first cache management module, and a first cache area,

the second computer comprises a virtualization mechanism, multiple OSs (Operating System) run on the virtualization mechanism, and the multiple OSs comprise an OS for running a second application program, and at least one OS comprising a second cache management module and a second cache management table,

the first application program and/or the second application program send(s) an access request to the second cache management module, the second cache management module;

(A) receives the access request from the first application program and/or the second application program;

(B) references the second cache management table to identify a storage location of access-target data conforming to the access request;

(C) sends a data transfer request to a first cache management module which stores the access-target data in a case where the access-target data exists in the first cache area; and

(D) acquires the access-target data from the second storage device in a case where the access-target data does not exist in the first cache area, in the case of the (C), the first cache management module acquires the access-target data conforming to the data transfer request from a relevant first cache area, and sends the access-target data to the second cache management module, and

the second cache management module sends the acquired access-target data or the received access-target data to the first application program and/or the second application program, which are/is the source of the access request.

2. A computer system according to claim 1, wherein the second computer comprises multiple second cache areas and a third cache area,

each of the multiple first cache areas is associated with one of the second cache areas,

the second cache management table stores information of the second cache area, the third cache area, and the second storage device,

the first cache area and the third cache area are physical cache areas,

the second cache area is a virtual cache area, and

the second cache management module determines a relevant first computer comprising a relevant first cache area corresponding to a relevant second cache area by identifying a relevant second cache area which stores access-target data conforming to the access request. c

3. A computer system according to claim 1, wherein the first computer further comprises a first cache management table,

the second cache management table stores information of the first cache area,

the first application program sends an access request to the first cache management module,

the first cache management module references the first cache management table, and in a case where the access-target data is in the first cache area, acquires the access-target data from the first cache area without sending the access request to the second computer, and in a case where the access-target data is not in the target first cache area, sends the access request to the second computer, acquires the access-target data from the second computer, and sends the acquired access-target data to the first application program.

8. A computer system according to claim 1, wherein the first cache management module sends the access request to the second computer even when the access-target data is in the target first cache area, and in the (B), in a case where the access target data is in the target first cache area, the second computer reads the access-target data from the target first cache area.

9. A computer system according to claim 1, wherein, in a case where the access target data is in the target first cache area, the first cache management module does not send the access request to the second computer, and

in a case where the access target data is not in the target first cache area, sends the access request to the second computer.

4. A computer system, comprising:

multiple first computers, which each comprise a first cache area; and

a second computer, which comprises a second storage device,

wherein the second computer comprises a function for managing the first cache areas of the multiple first computers,

each of the multiple first computers further comprises a first application program and a first cache management module,

the second computer comprises a second cache management module, multiple second cache areas, a third cache area, and a second cache management table,

each of the multiple first cache areas is associated with one of the second cache areas,

the first cache area and the third cache area are physical cache areas, the second cache area is a virtual cache area,

a target first computer is any first computer of the multiple first computers, and

a target first application program of the target first computer sends an access request to the second computer via the first cache management module of the target first computer,

the second cache management module;

(A) receives the access request from the first application program;

(B) references the second cache management table to identify a storage location of access-target data conforming to the access request; and

(C) in a case where the access-target data exists in the second cache area, sends a data transfer request to a relevant first cache management module of the target first computer, which comprises a target first cache area corresponding to the second cache area,

the relevant first cache management module acquires the access-target data conforming to the data transfer request from the target first cache area, and sends the access-target data to the second cache management module, and

the second cache management module sends the received access-target data to the first application program.

5. A computer system according to claim 4, wherein the second computer comprises an extended cache area of the multiple first cache areas, the second computer manages a capacity of the multiple first cache areas,

in a case where a capacity overrun of a target first cache area has been detected, the second computer migrates a migration-target data from the target first cache area to the extended cache area, and

in the (B), in a case where the read-target data is in the extended cache area, the second cache management module reads the read-target data from the extended cache area.

6. A computer system according to claim 5, wherein the second computer comprises a shared cache area, which is a cache area used in common by the multiple first computers,

in a case where access-target data requested from the target first computer has been stored in a different first cache area from the target first cache area, the second cache management module writes the access target data read from the first cache area to the shared cache area, and in the (B), in a case where the access target data is in the shared cache area, the second cache management module reads the access-target data from the shared cache area in a case where the access target data is also in the first cache area.

7. A computer system according to claim 6, wherein in a case where data, which duplicates the migration-target data, is in the extended cache area, and a used capacity of the shared cache area exceeds the capacity of the shared cache area when the redundant data is written to the shared cache area, the second cache management module writes data of a size that is equal to or larger than the size of the redundant data from the shared cache area to the storage device, and migrates the redundant data to the shared cache area from the extended cache area.

10. A cache control method performed by a second computer, which is coupled to multiple first computers and manages a second storage device,

wherein each of the multiple first computers comprises a first application program, a first cache management module, and a first cache area,

the second computer comprises a virtualization mechanism,

multiple OSs (Operating System) run on the virtualization mechanism, and the multiple OSs comprise an OS for running a second application program, and at least one OS comprising a second cache management module and a second cache management table,

the first application program and/or the second application program send(s) an access request to the second cache management module, the cache control method comprising the steps of, by the second cache management module:

(a) receiving the access request from the first application program and/or the second application program;

(b) referencing the second cache management table to identify a storage location of access-target data conforming to the access request;

(c) sending a data transfer request to a first cache management module which stores the access-target data, and acquiring the access-target data conforming to the data transfer request from a relevant first cache area in a case where the access-target data exists in the first cache area;

(d) acquiring the access-target data from the second storage device in a case where the access-target data does not exist in the first cache area; and

(e) sending the acquired access-target data or the received access-target data to the first application program and/or the second application program, which are/is the source of the access request.

11. A cache control method according to claim 10, wherein the second computer comprises multiple second cache areas and a third cache area, each of the multiple first cache areas is associated with one of the second cache areas,

the second cache management table stores information of the second cache area, the third cache area, and the second storage device,

the first cache area and the third cache area are physical cache areas,

the second cache area is a virtual cache area, and

the second cache management module determines a relevant first computer comprising a relevant first cache area corresponding to a relevant second cache area by identifying a relevant second cache area which stores access-target data conforming to the access request.

12. A cache control method performed by a second computer, which is coupled to multiple first computers and manages a second storage device,

wherein the second computer comprises a function for managing the first cache areas of the multiple first computers,

each of the multiple first computers comprises a first application program, a first cache management module, and a first cache area, the second computer comprises a second cache management module, multiple second cache areas, a third cache area, and a second cache management table,

each of the multiple first cache areas is associated with one of the second cache areas,

the first cache area and the third cache area are physical cache areas, the second cache area is a virtual cache area,

a target first computer is any first computer of the multiple first computers, and

a target first application program of the target first computer sends an access request to the second computer via the first cache management module of the target first computer,

the cache control method comprising the steps of, by the second cache management module:

(a) receiving the access request from the first application program;

(b) referencing the second cache management table to identify a storage location of access-target data conforming to the access request;

(c) sending a data transfer request to a relevant first cache management module of the target first computer, which comprises a target first cache area corresponding to the second cache area, and acquiring the access-target data conforming to the data transfer request from the target first cache area in a case where the access-target data exists in the second cache area; and

(d) sending the received access-target data to the first application program.

13. A cache control method according to claim 12, wherein the second computer comprises an extended cache area of the multiple first cache areas,

the second computer manages a capacity of the multiple first cache areas,

in a case where a capacity overrun of a target first cache area has been detected, the second computer migrates a migration-target data from the target first cache area to the extended cache area, and

in the (b), in a case where the read-target data is in the extended cache area, the second cache management module reads the read-target data from the extended cache area.

14. A computer program for execution by a second computer, which is coupled to multiple first computers and manages a second storage device,

wherein each of the multiple first computers comprises a first application program, a first cache management module, and a first cache area,

the computer program comprises a virtualization mechanism, multiple OSs (Operating System) run on the virtualization mechanism, and the multiple OSs comprise an OS for running a second application program, and at least one OS comprising a second cache management module and a second cache management table,

the first application program and/or the second application program send(s) an access request to the second cache management module, and the second cache management module:

(a) receives the access request from the first application program and/or the second application program;

(b) references the second cache management table to identify a storage location of access-target data conforming to the access request;

(c) sends a data transfer request to a first cache management module which stores the access-target data, and acquires the access-target data conforming to the data transfer request from the relevant first cache area in a case where the access-target data exists in the first cache area;

(d) acquires the access-target data from the second storage device in a case where the access-target data does not exist in the first cache area; and

(e) sends the acquired access-target data or the received access-target data to the first application program and/or the second application program, which are/is the source of the access request.

15. A computer program for execution by a second computer, which is coupled to multiple first computers and manages a second storage device,

wherein the computer program comprises a function for managing the first cache areas of the multiple first computers,

each of the multiple first computers comprises a first application program, a first cache management module, and a first cache area, the second computer comprises multiple second cache areas, a third cache area, and a second cache management table,

each of the multiple first cache areas is associated with one of the second cache areas,

the first cache area and the third cache area are physical cache areas,

the second cache area is a virtual cache area,

the target first computer is any first computer of the multiple first computers, and

a target first application program of the target first computer sends an access request to the second computer via the first cache management module of the target first computer,

wherein the computer program:

(a) receives the access request from the first application program;

(b) references the second cache management table to identify a storage location of access-target data conforming to the access request;

(c) sends a data transfer request to a relevant first cache management module of the target first computer, which comprises a target first cache area corresponding to the second cache area, and acquires the access-target data conforming to the data transfer request from the target first cache area in a case where the access-target data exists in the second cache area; and

(d) sends the acquired access-target data or the received access-target data to the first application program.