METHOD AND SYSTEM FOR ENSURING RELIABILITY OF CACHE DATA AND METADATA SUBSEQUENT TO A REBOOT

• US 20150242321A1
• Filed: 05/11/2015
• Published: 08/27/2015
• Est. Priority Date: 09/15/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Iyigun, Mehmet, Bak, Yevgeniy, Michael, Michael, Fields, David, Ergan, Cenk, Kirshenbaum, Alexander
• Granted Patent: US 10,387,313 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: G06F 12/0833 in combination with broadcast means (e.g. for invalidation or updating)
• 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 12/128 adapted to multidimensional cache systems, e.g. set-associative, multicache, multiset or multilevel
• CPC Class Codes: G06F 12/14 Protection against unauthorised use of memory or access to memory
• CPC Class Codes: G06F 2212/1052 Security improvement
• CPC Class Codes: G06F 2212/2022 Flash memory
• CPC Class Codes: G06F 2212/2146 being detachable, e.g.. USB memory
• CPC Class Codes: G06F 2212/222 Non-volatile memory
• CPC Class Codes: G06F 2212/466 Metadata, control data
• CPC Class Codes: G06F 2212/62 Details of cache specific to multiprocessor cache arrangements
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

To ensure that the contents of a non-volatile memory device cache may be relied upon as accurately reflecting data stored on disk storage, it may be determined whether the cache contents and/or disk contents are modified during a power transition, causing cache contents to no longer accurately reflect data stored in disk storage. The cache device may be removable from the computer, and unexpected removal of the cache device may cause cache contents to no longer accurately reflect data stored in disk storage. Cache metadata may be managed during normal operations and across power transitions, ensuring that cache metadata may be efficiently accessed and reliably saved and restored across power transitions. A state of a log used by a file system may be determined prior to and subsequent to reboot of an operating system in order to determine whether data stored on a cache device may be reliably used.

Claims

1. A method performed on a computing device that includes at least one processor and memory, the method comprising:

tracking, by the computing device, writes of data items to a mass storage device;

writing, by the computing device in response to the tracking, the data items to a cache device;

bringing the cache device offline subsequent to the data items being written to the cache device;

further tracking, by the computing device, writes of additional data items to the mass storage device while the cache device is offline;

bringing the cache device back online subsequent to the additional data items being written to the mass storage device; and

updating, by the computing device subsequent to the bringing the cache device back online, the cache device with the tracked additional data items.

2. The method of claim 1 where the tracking, the writing, and the bringing the cache device offline are part of a process performed during a shutdown of the computing device.

3. The method of claim 1 where the further tracking, the bringing the cache device back online, and the updating are part of a process performed during a restart of the computing device.

4. The method of claim 1 further comprising evicting at least a portion of contents of the cache device.

5. The method of claim 1 where the tracking begins upon initiation of a shutdown of the computing device.

6. The method of claim 1 where the further tracking is performed during startup of the computing device.

7. The method of claim 1 where the updating begins subsequent to a restart of the computing device.

8. A system comprising:

a computing device that includes at least one processor and memory;

a write recorder configured to track writes of data items by the computing device to a mass storage device;

the computing device configured to write, in response to the tracked writes, the data items to a cache device;

the computing device further configured to bring the cache device offline subsequent to the data items being written to the cache device;

the write recorder configured to further track writes of additional data items to the mass storage device while the cache device is offline;

the computing device further configured to bring the cache device back online subsequent to the additional data items being written to the mass storage device; and

a cache manager configured to update, subsequent to the cache device being brought back online, the cache device with the tracked additional data items.

9. The system of claim 8 where the writes are tracked, the data items are written to the cache device, and the cache device is brought offline during a shutdown of the computing device.

10. The system of claim 8 where the further writes are tracked, the cache device is brought back online, and the cache device is updated during a restart of the computing device.

11. The system of claim 8, the cache manager further configured to evict at least a portion of contents of the cache device.

12. The system of claim 8 where the write recorder is further configured to begin tracking the writes of the data items upon initiation of a shutdown of the computing device.

13. The system of claim 8 where the write recorder is further configured to begin further tracking the writes of the additional data items during startup of the computing device.

14. The system of claim 8 where the cache manager is further configured to update the cache device with the tracked additional data items subsequent to a restart of the computing device.

15. At least one computer storage medium comprising:

memory that comprises instructions that, based on execution by at least one processor of a computing device, configure the computing device to perform actions comprising;

tracking, by the computing device, writes of data items to a mass storage device;

writing, by the computing device in response to the tracking, the data items to a cache device;

bringing the cache device offline subsequent to the data items being written to the cache device;

further tracking, by the computing device, writes of additional data items to the mass storage device while the cache device is offline;

bringing the cache device back online subsequent to the additional data items being written to the mass storage device; and

updating, by the computing device subsequent to the bringing the cache device back online, the cache device with the tracked additional data items.

16. The at least one computer storage medium of claim 15 where the tracking, the writing, and the bringing the cache device offline are part of a process performed during a shutdown of the computing device.

17. The at least one computer storage medium of claim 15 where the further tracking, the bringing the cache device back online, and the updating are part of a process performed during a restart of the computing device.

18. The at least one computer storage medium of claim 15, the actions further comprising evicting at least a portion of contents of the cache device.

19. The at least one computer storage medium of claim 15 where the tracking begins upon initiation of a shutdown of the computing device, or where the further tracking is performed during startup of the computing device.

20. The at least one computer storage medium of claim 15 where the updating begins subsequent to a restart of the computing device.