File system and data caching method thereof

• US 20020091902A1
• Filed: 08/20/2001
• Published: 07/11/2002
• Est. Priority Date: 01/10/2001
• Status: Abandoned Application

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Hirofuji, Susumu
• Application Number:
  US09/931,917
• Publication Number:
  US 20020091902A1
• Time in Patent Office: Days
• US Class Current: 711/133
• CPC Class Codes: G06F 12/0862 with prefetch
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 12/126 with special data handling, e.g. priority of data or instructions, handling errors or pinning
• CPC Class Codes: G06F 16/172 Caching, prefetching or hoarding of files
• CPC Class Codes: G06F 2212/463 File
• CPC Class Codes: G06F 2212/468 The specific object being partially cached
• CPC Class Codes: G06F 3/0611 in relation to response time
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0683 Plurality of storage devices

Abstract

A file system composed of a computer having a host interface driver, a disk array system, and a cache memory, the file system that can improve the prediction accuracy to a data access request and the use efficiency of the cache memory, and can speed up a response to the request.

Claims

1. A file system comprising:

a first memory to store files in units of data block;

a second memory the access speed of which is faster than the first memory'"'"'s;

means for requesting to be provided with a file stored in the first memory;

means for recognizing a file of which access frequency is higher than a predetermined value and data blocks composing the recognized file; and

a controller which stores copy of a part or the whole of the composing data blocks in the second memory, and reads data blocks composing the requested file from the second memory at the request means'"'"' request if it is stored in the second memory or reads data blocks composing the requested file from the first memory if not.

2. The system of claim 1, wherein:

the recognizing means detects a close of the recognized file and notifies the controller of the close; and

the controller lowers the copy'"'"'s order of priority in the second memory when receiving the notification.

3. The system of claim 1, wherein:

the recognizing means detects a close of the recognized file and notifies the controller of the close; and

the controller deletes the copy from the second memory when receiving the notification.

4. The system of claim 1, wherein:

the first memory is a hard disk; and

the second memory is a cache memory.

5. The system of claim 1, wherein:

The file system, wherein;

the first memory is a plurality of hard disks each of which has a plurality of partitions;

the second memory is a cache memory;

the recognizing means recognizes a partition of which access frequency is higher than a predetermined value; and

the controller changes the data arrangement in the hard disks to increase the disk parallelism.

6. The system of claim 5, wherein:

the controller changes all the striping size in the hard disks to increase the disk parallelism.

7. The system of claim 1, wherein:

the recognizing means recognizes the higher access frequency file based on whether the file is accessed within a predetermined time of a former access.

8. The system of claim 7, wherein:

the recognizing means detects the file close based on whether the recognized file is not accessed within a predetermined time of a former access.

9. The system of claim 1, wherein:

the recognizing means determines for each file whether data blocks composing the file tends to be sequentially accessed or randomly accessed, and notifies the controller of the result; and

the controller allows more data blocks to be stored in the second memory when the file tends to be randomly accessed than when it tends to be sequentially accessed.

10. A data caching method, comprising:

storing files in a first memory in units of data block;

receiving a request to read a file stored in the first memory;

recognizing a file of which access frequency is higher than a predetermined value;

recognizing data blocks composing the recognized file;

storing copy of a part or the whole of the composing data blocks in the second memory, the access speed of which is faster than the first memory'"'"'s;

determining whether the data blocks composing the requested file is stored in the second memory; and

reading the composing data blocks from the second memory if it is stored in the second memory or from the first memory if not.

11. The method of claim 10, further comprising:

detecting a close of the recognized file; and

lowering the copy'"'"'s order of priority in the second memory when the close is detected.

12. The method of claim 10, further comprising:

detecting a close of the recognized file; and

deleting the copy from the second memory when the close is detected.

13. The method of claim 10, wherein:

the first memory is a hard disk; and

the second memory is a cache memory.

14. The method of claim 10, wherein:

the first memory is a plurality of hard disks each of which has a plurality of partitions;

the second memory is a cache memory;

the method, further comprising;

recognizing a partition of which access frequency is higher than a predetermined value; and

changing the data arrangement in the hard disks to increase the disk parallelism.

15. The method of claim 14, wherein:

the changing includes changing all the striping size in the hard disks to increase the disk parallelism.

16. The method of claim 10, further comprising:

recognizing the higher access frequency file based on whether the file is accessed within a predetermined time of a former access.

17. The method of claim 16, further comprising:

detecting the file close based on whether the recognized file is not accessed within a predetermined time of a former access.

18. The method of claim 10, further comprising:

determining for each file whether data blocks composing the file tends to be sequentially accessed or randomly accessed; and

allowing more data blocks to be stored in the second memory when the file tends to be randomly accessed than when it tends to be sequentially accessed.