Technique for migrating data between storage devices for reduced power consumption

• US 6,732,241 B2
• Filed: 09/07/2001
• Issued: 05/04/2004
• Est. Priority Date: 09/07/2001
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Riedel, Erik
• Primary Examiner(s): Kim, Matthew
• Assistant Examiner(s): ELMORE, STEPHEN C
• Application Number:
  US09/948,362
• Publication Number:
  US 20030051104A1
• Time in Patent Office: 970 Days
• Field of Search: 711/154, 711/100, 711/167, 365/227
• US Class Current: 711/154
• CPC Class Codes: G06F 1/3225 of memory devices
• CPC Class Codes: G06F 1/3275 Power saving in memory, e.g. RAM, cache
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A method of and apparatus for migrating data between storage devices for reducing power consumption. Unlike prior techniques for conserving power by spinning down a magnetic disk (e.g., in a laptop computer), the present invention migrates data based on the assumption that the disk is maintained spinning (e.g., in a server). Accordingly, the incremental power consumed by maintaining data on the disk is nominal in comparison to the amount of power required to store the data in volatile memory (e.g., RAM). Data placement is largely based on the goal of minimizing power consumption during periods when the data is not being accessed. Further, unlike conventional techniques in which data is removed from RAM only when a better candidate is available to replace the data, the present invention may move data from RAM regardless of whether replacement data is available. This is avoids consumption of power to maintain data in RAM that is idle. Thus, under certain conditions, the inventive technique for data migration in a computer system reduces power consumption in comparison to conventional algorithms.

Claims

1. An apparatus for migrating data between storage devices in a computer system having a first memory device and a second memory device, the first memory device requiring more power to maintain a data block valid than the second memory device, wherein the data block is moved from the first memory device to the second memory device when an anticipated amount of time before a next access to the data block exceeds a predetermined threshold.

2. The apparatus according to claim 1, wherein the data block is moved from the first memory device to the second memory device regardless of whether a replacement data block is available.

3. The apparatus according to claim 1, wherein the first memory device includes random access memory (RAM).

4. The apparatus according to claim 3, wherein the second memory device includes a magnetic disk.

5. The apparatus according to claim 3, wherein the magnetic disk is maintained in its spinning condition.

6. The apparatus according to claim 3, wherein the second memory device includes flash memory.

7. The apparatus according to claim 1, wherein the first memory device requires repeated refreshing.

8. The apparatus according to claim 7, wherein the second memory device does not require refreshing.

9. A method of migrating data between storage devices in a computer system, comprising steps of:

a. assigning a data block to a first memory device of the computer system;

b. computing an anticipated amount of time before a next access to the data block; and

c. moving the data block from the first memory device to a second memory device of the computer system when the anticipated amount of time before a next access to the data block exceeds a predetermined threshold.

10. The method according to claim 9, wherein the first memory device requires more power to maintain the data block than the second memory device.

11. The method according to claim 9, wherein the data block is moved from the first memory device to the second memory device regardless of whether a replacement data block is available.

12. The method according to claim 9, wherein the first memory device includes random access memory (RAM).

13. The method according to claim 12, wherein the second memory device includes a magnetic disk.

14. The method according to claim 13, wherein the magnetic disk is maintained in its spinning condition.

15. The method according to claim 13, wherein the second memory device includes flash memory.

16. The method according to claim 9, wherein the first memory device requires repeated refreshing.

17. The method according to claim 16, wherein the second memory device does not require refreshing.

18. An apparatus for migrating data between storage devices in a computer system having a first memory device, a second memory device and a third memory device, wherein a data block is moved from the first memory device to the second memory device in response to an anticipated time until a next access to the data block for reading or writing and wherein the data block is moved from the first memory device to the third memory device in response to an anticipated time until a next read access to the data block being different from an anticipated time until a next write access to the data block.

19. The apparatus according to claim 18, wherein the data block is moved from the first memory device to the second memory device when the anticipated amount of time before a next read access to the data block exceeds a first predetermined threshold and an anticipated amount of time before the next write access to the data block exceeds a second predetermined threshold and wherein the data block is moved from the first memory device to the third memory device when the anticipated amount of time before the next read access to the data block does not exceed the first predetermined threshold and the anticipated amount of time before the next write operation exceeds the second predetermined threshold.

20. The apparatus according to claim 18, wherein the data block is moved from the first memory device to the second or third memory device regardless of whether a replacement data block is available.

21. The apparatus according to claim 18, wherein the first memory device includes random access memory (RAM).

22. The apparatus according to claim 21, wherein the second memory device includes a magnetic disk.

23. The apparatus according to claim 22, wherein the magnetic disk is maintained in its spinning condition.

24. The apparatus according to claim 22, wherein the third memory device includes flash memory.

25. The apparatus according to claim 18, wherein the first memory device requires more power to maintain the data block valid than the second memory device.

26. The apparatus according to claim 18, wherein the first memory device requires repeated refreshing.

27. The apparatus according to claim 26, wherein the second memory device does not require refreshing.

28. The apparatus according to claim 27, wherein the third memory device has a write latency that is significantly higher than its read latency.

29. The apparatus according to claim 27, wherein the third memory device requires significantly more power to perform a write operation than a read operation.

30. The apparatus according to claim 18, wherein the third memory device has a write latency that is significantly higher than its read latency.

31. The apparatus according to claim 18, wherein the third memory device requires significantly more power to perform a write operation than a read operation.

32. A method of migrating data between storage devices in a computer system, comprising steps of:

a. assigning a data block to a first memory device of the computer system;

b. computing an anticipated amount of time before a next write access to the data block;

c. removing the data block from the first memory device when the anticipated amount of time until the next write access to the data block exceeds a first threshold;

d. computing an anticipated amount of time before a next read access to the data block; and

e. inserting the data block into a second memory device of the computer system when the anticipated time until the next read access to the data block exceeds a second threshold;

otherwise, inserting the data block into a third memory device of the computer system.

33. The method according to claim 32, wherein the third memory device has a write latency that is significantly higher than its read latency.

34. The method according to claim 32, wherein the third memory device requires significantly more power to perform a write operation than a read operation.