COMPUTER SYSTEM AND CONTROL METHOD

• US 20160132433A1
• Filed: 07/29/2013
• Published: 05/12/2016
• Est. Priority Date: 07/29/2013
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: HAYASHI, Shinichi, FUNAYA, Yusuke
• Granted Patent: US 9,703,717 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 12/0888 using selective caching, e.g. bypass
• CPC Class Codes: G06F 2212/604 Details relating to cache allocation
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/0649 Lifecycle management
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0685 Hybrid storage combining heterogeneous device types, e.g. hierarchical storage, hybrid arrays

Abstract

A computer system according to the present invention is composed of a server 200 having a flash memory drive 204 for cache, a storage system 260 having storage tiers composed of an SSD 267 and an HDD 268, and a management server having a page tier determination program 503 for determining the storage tier to which data is to be stored. The page tier determination program 503 migrates data having a high read access rate out of the pages having a high cache rate to the flash memory drive 204 to a storage tier of the HDD 268, and confirms so that data is not stored in a duplicated manner to the flash memory drive 204 and the SSD 267. Further, the data having a relatively high write access rate is migrated to the storage tier of the SSD 267 so as to prevent deterioration of write process performance.

Claims

1. A computer system comprising:

a storage system having a first storage media, and a second storage media which is a storage media having a higher access performance than the first storage media;

a server having a server cache; and

a management server;

wherein the storage system provides to the server a volume having multiple fixed length areas to which a storage area from the first or the second storage media is allocated, and stores data written to the fixed length area from the server to the allocated storage area of the first or second storage media;

the storage system has a volume management information for storing, for each fixed length area, a number of read accesses and a number of write accesses that has occurred within a certain period of time from the server to the fixed length area;

the server caches a portion of the data stored in the volume to the server cache, and has a cache control information storing information related to the cached data to the server cache;

wherein the management server acquires the volume management information from the storage system;

acquires the cache control information from the server;

calculates, based on the volume management information and the cache control information, a server cache rate which is a rate of data within the fixed length area being cached in the server cache for each fixed length area, and a read rate which is a ratio of a number of read accesses with respect to a sum of the number of read accesses and a number of write accesses that has occurred within the certain period of time from the server to the fixed length area; and

determines which storage area of the first and second storage media should be allocated to each fixed length area based on the server cache rate and the read rate.

2. The computer system according to claim 1, wherein

if the read rate of the fixed length area exceeds a first threshold value, it is determined that the first storage media is allocated to the fixed length area.

3. The computer system according to claim 1, wherein

if the read rate of the fixed length area falls below a second threshold value, it is determined that the second storage media is allocated to the fixed length area.

4. The computer system according to claim 1, wherein

the server has a database program for storing and managing one or a plurality of objects to the volume;

the database program is executed by the server to manage location information of each object specifying where in the volume said each of the object is stored; and

the management server computes a read rate and a server cache rate of each object based on the volume management information, the cache control information and the location information, and based on the read rate and the server cache rate of each object, determines to which storage media, the first storage media or the second storage media, the object is to be placed.

5. The computer system according to claim 1, wherein

out of the multiple fixed storage length areas, the storage system caches data of a fixed length area to which the storage area of the first storage media is allocated to a portion of the storage area of the second storage media.

6. The computer system according to claim 5, wherein

the management server acquires information related to a status of the plurality of fixed length areas at a designated time point, and after acquisition thereof, based on an instruction from a user, returns the status of the plurality of fixed length areas to a status at the designated time point based on the acquired status of the plurality of the fixed length areas.

7. The computer system according to claim 6, wherein

said information related to the status of the plurality of fixed length areas is one or more of the following information:

information stating whether the storage area allocated to the plurality of fixed length areas is from the first storage media or from the second storage media;

information regarding the area to which data is cached to the server cache out of the plurality of fixed length areas; and

information regarding the area to which data is cached in the storage area of the second storage media out of the fixed length area to which the storage area of the first storage media is allocated.

8. A method for controlling a computer system comprising:

a storage system having a first storage media, and a second storage media which is a storage media having a higher access performance than the first storage media;

a server having a server cache; and

a management server;

wherein the storage system provides to the server a volume having multiple fixed length areas to which a storage area from the first or the second storage media is allocated, and stores data written to the fixed length area from the server to the allocated storage area of the first or second storage media;

the storage system stores a volume management information for storing, for each fixed length area, a number of read accesses and a number of write accesses that has occurred within a certain period of time from the server to the fixed length area;

the server stores information related to the data cached to the server cache in the cache control information when a portion of the data stored in the volume is cached to the server cache;

wherein the management server

acquires the volume management information and the cache control information, and based on the acquired volume management information and the cache control information, calculates a server cache rate which is a rate of data out of the fixed length area being cached in the server cache for each fixed length area, and a read rate which is a ratio of a number of read accesses with respect to a sum of the number of read accesses and a number of write accesses that has occurred within the certain period of time from the server to the fixed length area; and

determines which storage area of the first and second storage media should be allocated to each fixed length area based on the server cache rate and the read rate.

9. The method for controlling a computer system according to claim 8, wherein

if the read rate of the fixed length area exceeds a first threshold value, it is determined that the first storage media is allocated to the fixed length area.

10. The method for controlling a computer system according to claim 8, wherein

if the read rate of the fixed length area falls below a second threshold value, it is determined that the second storage media is allocated to the fixed length area.

11. The method for controlling a computer system according to claim 8, wherein

the server has a database program for storing and managing one or a plurality of objects to the volume;

the database program is executed by the server to manage location information of each object specifying where in the volume said each of the object is stored; and

the management server computes a read rate and a server cache rate of each object based on the volume management information, the cache control information and the location information, and based on the read rate and the server cache rate of each object, determines to which storage media, the first storage media or the second storage media, the object is to be placed.

12. The method for controlling a computer system according to claim 8, wherein

out of the multiple fixed storage length areas, the storage system caches data of a fixed length area to which the storage area of the first storage media is allocated to a portion of the storage area of the second storage media.

13. The method for controlling a computer system according to claim 12, wherein

the management server acquires information related to a status of the plurality of fixed length areas at a designated time point, and after acquisition thereof, based on an instruction from a user, returns the status of the plurality of fixed length areas to a status at the designated time point based on the acquired status of the plurality of the fixed length areas.

14. The method for controlling a computer system according to claim 13, wherein

said information related to the status of the plurality of fixed length areas is one or more of the following information:

information stating whether the storage area allocated to the plurality of fixed length areas is from the first storage media or from the second storage media;

information regarding the area to which data is cached to the server cache out of the plurality of fixed length areas; and

information regarding the area to which data is cached in the storage area of the second storage media out of the fixed length area to which the storage area of the first storage media is allocated.

15. A computer system comprising:

a storage system having a first storage media, and a second storage media which is a storage media having a higher access performance than the first storage media;

a server having a server cache; and

a management server;

wherein the storage system provides to the server a volume having multiple fixed length areas to which a storage area from the first or the second storage media is allocated, and stores data written to the fixed length area from the server to the allocated storage area of the first or second storage media;

the server caching a portion of the data stored in the volume to the server cache, and having a cache control information storing information related to the cached data to the server cache;

wherein the management server acquires information from the storage system on whether the storage area allocated to each of the plurality of fixed length areas is of a first storage media or of a second storage area, and transmits the information to the server; and

based on the information, if the storage area allocated to the fixed length area is determined as the area of the first storage media, the server caches the data in the fixed length area to the server cache, and if the storage area allocated to the fixed length area is determined as the second storage media, the server does not cache the data in the fixed length area to the server cache.