System and method for caching data on a hard disk drive

• US 8,055,841 B2
• Filed: 02/19/2009
• Issued: 11/08/2011
• Est. Priority Date: 02/19/2009
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Breslau, Franklin Charles, Pomerantz, Ori
• Primary Examiner(s): NGUYEN, THAN VINH
• Application Number:
  US12/388,599
• Publication Number:
  US 20100211730A1
• Time in Patent Office: 992 Days
• Field of Search: None
• US Class Current: 711/113
• 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 2212/313 In storage device
• CPC Class Codes: G06F 2212/462 Track or segment

Abstract

A method for caching data on a hard disk drive. The method begins by identifying at least one track residing on the hard disk drive to devote to caching. The method continues with determining an average for each data value both residing on the hard disk drive and not residing in random access memory. The average value being the average number of times a given data value was read into memory before being the given data value was overwritten. Next the method detects a period of hard disk activity and in response to detecting, the method concludes by copying to each cache track each data value not residing in random access memory and having an average which exceeds a first threshold.

Claims

1. A method for caching data on a hard disk drive, said method comprising:

identifying at least one track to devote to said caching, each track of said at least one track residing on said hard disk drive;

determining an average for each data value both residing on said hard disk drive and not residing in random access memory, said average being the average number of times a given data value was read into memory before said given data value is overwritten;

detecting a period of hard disk activity; and

in response to said detecting, copying to each track of said at least one track each data value not residing in said random access memory and having an average which exceeds a first threshold.

2. The method of claim 1, said identifying further comprising:

selecting each track of said at least one track in such a way that a distance measured in time between two consecutive selected tracks does not exceed a second threshold, said second threshold being provided by said end user prior to said selecting.

3. The method of claim 1, where said average value being calculated according to a function

4. The method of claim 1, where said period of hard disk drive activity is a time established by said end user prior to said detecting.

5. The method of claim 1, where said period of hard disk drive activity is a time at which both reading from and writing to said hard disk drive falls below a third threshold, said third threshold being provided by said end user prior to said detecting.

6. The method of claim 1, where all said data values having been copied to each track of said at least one track collectively do not exceed a capacity of the inner most track of said at least one track identified according to said identifying.

7. A computer program product, comprising a computer-usable storage medium having a computer-readable program code stored therein, said computer-readable program code containing instructions that when executed by a processor of a computer system implement a method for caching data on a hard disk drive, said method comprising:

identifying at least one track to devote to said caching, each track of said at least one track residing on said hard disk drive;

determining an average for each data value both residing on said hard disk drive and not residing in random access memory, said average being the average number of times a given data value was read into memory before said given data value is overwritten;

detecting a period of hard disk activity; and

in response to said detecting, copying to each track of said at least one track each data value not residing in said random access memory and having an average which exceeds a first threshold.

8. The computer program product of claim 7, said identifying further comprising:

selecting each track of said at least one track in such a way that a distance measured in time between two consecutive selected tracks does not exceed a second threshold, said second threshold being provided by said end user prior to said selecting.

9. The computer program product of claim 7, where said average value being calculated according to a function

10. The computer program product of claim 7, where said period of hard disk drive activity is a time established by said end user prior to said detecting.

11. The computer program product of claim 7, where said period of hard disk drive activity is a time at which both reading from and writing to said hard disk drive falls below a third threshold, said third threshold being provided by said end user prior to said detecting.

12. The computer program product of claim 7, where all said data values having been copied to each track of said at least one track collectively do not exceed a capacity of the inner most track of said at least one track identified according to said identifying.

13. A computing system comprising a processor coupled to a computer-readable memory unit, said memory unit comprising a software application, said software application comprising instruction that when executed by said processor, implement a method for caching data on a hard disk drive, said method comprising:

identifying at least one track to devote to said caching, each track of said at least one track residing on said hard disk drive;

determining an average for each data value both residing on said hard disk drive and not residing in random access memory, said average being the average number of times a given data value was read into memory before said given data value is overwritten;

detecting a period of hard disk activity; and

in response to said detecting, copying to each track of said at least one track each data value not residing in said random access memory and having an average which exceeds a first threshold.

14. The computing system of claim 13, said identifying further comprising:

selecting each track of said at least one track in such a way that a distance measured in time between two consecutive selected tracks does not exceed a second threshold, said second threshold being provided by said end user prior to said selecting.

15. The computing system of claim 13, where said average value being calculated according to a function

16. The computing system of claim 13, where said period of hard disk drive activity is a time established by said end user prior to said detecting.

17. The computing system of claim 13, where said period of hard disk drive activity is a time at which both reading from and writing to said hard disk drive falls below a third threshold, said third threshold being provided by said end user prior to said detecting.

18. The computing system of claim 13, where all said data values having been copied to each track of said at least one track collectively do not exceed a capacity of the inner most track of said at least one track identified according to said identifying.

19. A process for supporting computer infrastructure, said process comprising providing at least one support service for at least one of creating, integrating, hosting, maintaining, and deploying computer-readable code in a computing system, wherein said code in combination with the computing system is capable of implementing a method for caching data on a hard disk drive, said method comprising:

identifying at least one track to devote to said caching, each track of said at least one track residing on said hard disk drive;

determining an average for each data value both residing on said hard disk drive and not residing in random access memory, said average being the average number of times a given data value was read into memory before said given data value is overwritten;

detecting a period of hard disk activity; and

in response to said detecting, copying to each track of said at least one track each data value not residing in said random access memory and having an average which exceeds a first threshold.

20. The process for supporting computer infrastructure of claim 19, said identifying further comprising:

selecting each track of said at least one track in such a way that a distance measured in time between two consecutive selected tracks does not exceed a second threshold, said second threshold being provided by said end user prior to said selecting.

21. The process for supporting computer infrastructure of claim 19, where said average value being calculated according to a function

22. The process for supporting computer infrastructure of claim 19, where said period of hard disk drive activity is a time established by said end user prior to said detecting.

23. The process for supporting computer infrastructure of claim 19, where said period of hard disk drive activity is a time at which both reading from and writing to said hard disk drive falls below a third threshold, said third threshold being provided by said end user prior to said detecting.

24. The process for supporting computer infrastructure of claim 19, where all said data values having been copied to each track of said at least one track collectively do not exceed a capacity of the inner most track of said at least one track identified according to said identifying.