Hybrid Checkpointed Memory

• US 20130332660A1
• Filed: 03/05/2013
• Published: 12/12/2013
• Est. Priority Date: 06/12/2012
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Fusion-IO Incorporated (Western Digital Corporation)
• Inventors: Talagala, Nisha, Sundararaman, Swaminathan, Piggin, Nick, Batwara, Ashish, Flynn, David
• Granted Patent: US 9,678,863 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 2201/815 Virtual middleware or OS functionality using virtual machines to implement generic software techniques for error detection or fault masking G06F11/1484
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency ensuring consistency in mirrored systems G06F11/2064
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

Apparatuses, systems, methods, and computer program products are disclosed for hybrid checkpointed memory. A method includes referencing data of a range of virtual memory of a host. The referenced data is already stored by a non-volatile medium. A method includes writing, to a non-volatile medium, data of a range of virtual memory that is not stored by the non-volatile medium. A method includes providing access to data of a range of virtual memory from a non-volatile medium using a persistent identifier associated with referenced data and written data.

Claims

1. A method for hybrid checkpointed memory, the method comprising:

referencing data of a range of virtual memory of a host, the referenced data already stored by a non-volatile medium;

writing, to the non-volatile medium, data of the range of virtual memory that is not stored by the non-volatile medium; and

providing access to the data of the range of virtual memory from the non-volatile medium using a persistent identifier associated with the referenced data and the written data.

2. The method of claim 1, further comprising copying at least a portion of the data of the range of virtual memory and providing write access to the copy while writing from the range of virtual memory to the non-volatile medium.

3. The method of claim 2, wherein the copied at least a portion of the data comprises data of a storage request received during checkpointing, the data copied in response to the storage request.

4. The method of claim 2, wherein the copied at least a portion of the data comprises data stored in volatile memory of the host and data stored on the non-volatile medium.

5. The method of claim 2, further comprising merging data of the copied at least a portion of the data with the data of the range of virtual memory in response to completing the writing.

6. The method of claim 1, further comprising providing access to a different version of the data of the range of virtual memory using a different persistent storage namespace identifier.

7. The method of claim 1, further comprising deleting one or more inconsistent versions of the data in response to recovering from a restart event and providing a consistent version of the data to a client.

8. The method of claim 1, further comprising receiving a snapshot request from a client for the range of virtual memory of the host, wherein the referencing and the writing are in response to the checkpoint request.

9. The method of claim 1, further comprising receiving a request from a client labeling the range of virtual memory as persistent.

10. The method of claim 1, wherein writing the data comprises writing the data not stored by the non-volatile medium from volatile memory of the host to an append point of a sequential log of the non-volatile medium.

11. The method of claim 10, wherein providing access to the data of the range of virtual memory comprises providing access to portions of the data located in the sequential log based on entries for the data in an address mapping structure.

12. The method of claim 1, wherein writing the data comprises copying the data and preserving the copied data on the non-volatile medium.

13. The method of claim 1, further comprising mapping multiple clones of the data into the virtual memory of the host.

14. The method of claim 13, further comprising merging updates to the multiple clones and storing the merged data on the non-volatile medium.

15. The method of claim 14, wherein merging the updates comprises resolving conflicts in the updates based on a collision detection policy for the data.

16. The method of claim 1, further comprising locating dirty pages in the range of virtual memory using a page table to determine which data is not stored by the non-volatile medium.

17. The method of claim 1, further comprising maintaining a has-been-written data structure indicating which data of the range of virtual memory has been written since a previous checkpoint at a sub-page granularity.

18. An apparatus for hybrid checkpointed memory, the apparatus comprising:

an extended memory module configured to use main memory of a host and a non-volatile recording medium as virtual memory for the host; and

a checkpoint module configured to destage data from the main memory to the non-volatile recording medium in response to a checkpoint request for the data.

19. The apparatus of claim 18, further comprising a storage namespace module configured to associate different filenames with the data in response to different checkpoint requests for the data.

20. The apparatus of claim 18, further comprising a clone module configured to make a write accessible copy of at least a portion of the virtual memory in response to the checkpoint event and to provide access to the write accessible copy while the checkpoint module destages the data.

21. A computer program product comprising a computer readable storage medium storing computer usable program code executable to perform operations for hybrid checkpointed memory, the operations comprising:

cloning data of a range of virtual memory in response to a checkpoint event for the range of virtual memory, the range of virtual memory comprising data stored in volatile memory and data stored in a non-volatile memory medium;

flushing dirty data of the range of virtual memory to the non-volatile memory medium in response to the checkpoint event; and

providing access to the data of the range of virtual memory while the dirty data is being flushed using one of the clone of the data and the data of the range of virtual memory.

22. The computer program product of claim 21, wherein the operations further comprise flushing data of the clone that is stored in the volatile memory and not in the non-volatile memory medium to the non-volatile memory medium in response to a subsequent checkpoint event and providing access exclusively to the flushed versions of the data such that access to the data transitions atomically between consistent states for the data.

23. The computer program product of claim 22, wherein the operations further comprise deleting one or more clones of the data after a restart event to prevent a client from accessing an inconsistent state of the data.

24. An apparatus for hybrid checkpointed memory, the apparatus comprising:

means for mapping multiple logical clones of a file into virtual memory of a host, the virtual memory backed by both volatile memory and non-volatile storage;

means for merging changes to the multiple logical clones of the file in virtual memory; and

means for checkpointing the merged changes to the non-volatile storage.