Non-volatile backup for data cache

• US 20060212644A1
• Filed: 03/21/2005
• Published: 09/21/2006
• Est. Priority Date: 03/21/2005
• Status: Abandoned Application

• Current Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Lee, Whay Sing, Acton, John D.
• Application Number:
  US11/086,100
• Publication Number:
  US 20060212644A1
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 1/30 Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations for resetting only G06F1/24
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: G06F 11/201 between storage system components
• CPC Class Codes: G06F 11/2015 Redundant power supplies power supply failure G06F1/30
• CPC Class Codes: G06F 11/2092 Techniques of failing over between control units
• CPC Class Codes: G06F 12/0804 with main memory updating G06F12/0806 takes precedence
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2201/88 Monitoring involving counting
• CPC Class Codes: G06F 2212/222 Non-volatile memory
• CPC Class Codes: G06F 2212/2228 Battery-backed RAM
• CPC Class Codes: G06F 2212/284 being distributed

Abstract

A non-volatile data cache having a cache memory coupled to an external power source and operable to cache data of an external data device such that access requests for the data can be serviced by the cache rather than the external device. A non-volatile data storage device is coupled to the cache memory. An uninterruptible power supply (UPS) is coupled to the cache memory and the non-volatile data storage device so as to maintain the cache memory and the non-volatile storage device in an operational state for a period of time in the event of an interruption in the external power source.

Claims

1. A non-volatile data cache comprising:

a cache memory coupled to an external power source and operable to cache data of an external data device such that access requests for the data can be serviced by the cache rather than the external device;

a non-volatile data storage device coupled to the cache memory;

an uninterruptible power supply (UPS) coupled to the cache memory and the non-volatile data storage device so as to maintain the cache memory and the non-volatile storage device in an operational state for a period of time in the event of an interruption in the external power source.

2. The non-volatile data cache of claim 1 wherein the period of time is selected to allow the contents of the cache memory to be copied to the non-volatile data storage device.

3. The non-volatile data cache of claim 1 wherein the cache memory comprises volatile memory devices.

4. The non-volatile data cache of claim 1 wherein the cache memory comprise dynamic random access memory (DRAM).

5. The non-volatile data cache of claim 1 wherein the cache memory comprise static random access memory (SRAM).

6. The non-volatile data cache of claim 1 wherein the cache memory comprises memory devices that are physically distributed.

7. The non-volatile data cache of claim 6 further comprising a physical cache manager coupled to the distributed memory devices, wherein the physical cache manager is operable to create a unified cache pool from the physically distributed memory devices.

8. The non-volatile data cache of claim 1 wherein the external data device comprises a number of virtualized storage volumes and the non-volatile data cache further comprises a plurality of logical cache managers, each of which manages caching functions for one or more of the virtualized storage volumes.

9. The non-volatile data cache of claim 1 wherein the non-volatile data storage device comprises at least one miniature disk drive.

10. The non-volatile data cache of claim 1 wherein the non-volatile data storage device comprises flash memory.

11. The non-volatile data cache of claim 1 wherein the non-volatile data storage device is physically located in a housing with the cache memory.

12. The non-volatile data cache of claim 1 wherein the UPS comprises an energy storage device holding less than 10 Watt hours of energy.

13. A data storage system comprising:

an external power source;

a plurality of mass storage devices;

a cache memory coupled to the external power source and operable to cache data from the plurality of mass storage devices;

a non-volatile data storage device coupled to the cache memory;

an uninterruptible power supply (UPS) coupled to the cache memory and the non-volatile data storage device so as to maintain the cache memory and the non-volatile storage device in an operational state for a period of time in the event of an interruption in the external power source.

14. The data storage system of claim 13 wherein the period of time is selected to allow the contents of the cache memory to be copied to the non-volatile data storage device.

15. The data storage system of claim 13 wherein the cache memory comprises volatile memory devices.

16. The data storage system of claim 13 wherein the cache memory comprise volatile random access memory.

17. The data storage system of claim 13 wherein the cache memory comprises memory devices that are physically distributed.

18. The data storage system of claim 17 further comprising a physical cache manager coupled to the distributed memory devices, wherein the physical cache manager is operable to create a unified cache pool from the physically distributed memory devices.

19. The data storage system of claim 13 wherein the plurality of mass storage devices are logically organized as a number of virtualized storage volumes and the non-volatile data cache further comprises a plurality of logical cache managers, each of which manages caching functions for one or more of the virtualized storage volumes.

20. The data storage system of claim 13 wherein the non-volatile data storage device comprises at least one miniature disk drive.

21. The non-volatile data cache of claim 13 wherein the non-volatile data storage device comprises flash memory.

22. A method of protecting data during storage access operations comprising:

caching data from one or more data storage devices in volatile storage using a write-back cache policy, wherein the volatile storage is powered by a primary power source; and

in event of interruption of the primary power source, copying cached data to a miniature storage device.

23. The method of claim 22 further comprising powering the volatile storage and the miniature storage device using a secondary power source that is independent of the primary power source.

24. The method of claim 22 further comprising removing power from the volatile storage after copying the cached data.

25. The method of claim 22 further comprising removing power from the miniature storage device after copying the cached data.

26. The method of claim 22 further comprising:

determining when the primary power source is restored; and

copying the cached data from the miniature storage device to the volatile storage.

27. The method of claim 22 wherein the miniature storage device comprises a miniature disk drive.

28. The method of claim 22 wherein the miniature storage device comprises a flash EEPROM memory.

29. A cache module implementing the method of claim 22.

30. A disk drive implementing the method of claim 22.

31. A data storage system implementing the method of claim 22.