Eventual consistency intent cleanup in a dispersed storage network

• US 10,248,495 B2
• Filed: 02/17/2017
• Issued: 04/02/2019
• Est. Priority Date: 02/17/2017
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Khadiwala, Ravi V., Motwani, Manish, Narubin, Renars W., Resch, Jason K., Scholl, Daniel J., Vedpathak, Yogesh R.
• Primary Examiner(s): Ko, Chae M
• Application Number:
  US15/435,552
• Publication Number:
  US 20180239669A1
• Time in Patent Office: 774 Days
• Field of Search: 714 62
• CPC Class Codes: G06F 11/0709 in a distributed system consisting of a plurality of standalone computer nodes, e.g. clusters, client-server systems
• CPC Class Codes: G06F 11/0727 in a storage system, e.g. in a DASD or network based storage system drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency ensuring consistency in mirrored systems G06F11/2064
• CPC Class Codes: G06F 9/54 Interprogram communication

Abstract

A method for execution by a dispersed storage (DS) cleanup unit includes determining a dead session of a DSN. A subset of a plurality of eventual consistency intent names is generated by identifying eventual consistency intent names that include a session identifier corresponding to the dead session in a prefix of the eventual consistency intent names, where the subset of the plurality of eventual consistency intent names corresponds to all eventual consistency intents of the dead session. A subset of storage units responsible for storing the all eventual consistency intents of the dead session is determined based on the prefix of the eventual consistency intent names in the subset. All eventual consistency intents of the dead session are retrieved from the subset of storage units, and execution of eventual consistency updates indicated in the all eventual consistency intents of the dead session is facilitated.

Claims

1. A method for execution by a dispersed storage (DS) cleanup unit of a dispersed storage network (DSN) that includes a processor, the method comprises:

determining a dead session of the DSN;

generating a subset of a plurality of eventual consistency intent names by identifying ones of the plurality of eventual consistency intent names that include a session identifier corresponding to the dead session in a prefix of the ones of the plurality of eventual consistency intent names, wherein the subset of the plurality of eventual consistency intent names corresponds to all eventual consistency intents of the dead session;

determining a subset of storage units responsible for storing the all eventual consistency intents of the dead session based on the prefix of the eventual consistency intent names in the sub set;

retrieving the all eventual consistency intents of the dead session from the subset of storage units; and

facilitating execution of eventual consistency updates indicated in the all eventual consistency intents of the dead session.

2. The method of claim 1, wherein generating the subset of the plurality of eventual consistency intent names includes generating a prefixed-based listing of the plurality of eventual consistency intent names.

3. The method of claim 1, wherein the session identifier in the prefix of each of the plurality of eventual consistency intent names maps to the subset of storage units, and wherein the subset of storage units is determined based on the session identifier corresponding to the dead session included in the prefix.

4. The method of claim 3, wherein the all eventual consistency intents of the dead session are stored in subsets of storage units mapped to the session identifier corresponding to the dead session.

5. The method of claim 1, wherein the DSN includes a plurality of storage sets, and wherein the subset of storage units is located in a same one of the plurality of storage sets.

6. The method of claim 5, wherein each storage set includes a plurality of stripes of storage units, and wherein the subset of storage units is located in a same one of the plurality of storage stripes in the same one of the plurality of storage sets.

7. The method of claim 1, wherein the plurality of eventual consistency intent names is generated by utilizing a name generation scheme based on a weighted rendezvous strategy.

8. The method of claim 1, wherein the dead session is associated with a computing device of the DSN, and wherein the dead session is determined based on the computing device crashing.

9. The method of claim 1, wherein the dead session is associated with a computing device of the DSN, and wherein the dead session is determined based on when the computing device encounters a network partition which prevents the computing device from accomplishing an eventual consistency update.

10. The method of claim 1, wherein the dead session is determined in response to receiving a notification via a network of the DSN.

11. A processing system of a dispersed storage (DS) cleanup unit comprises:

at least one processor;

a memory that stores operational instructions, that when executed by the at least one processor cause the processing system to;

determine a dead session of a DSN associated with the DS cleanup unit;

generate a subset of a plurality of eventual consistency intent names by identifying ones of the plurality of eventual consistency intent names that include a session identifier corresponding to the dead session in a prefix of the ones of the plurality of eventual consistency intent names, wherein the subset of the plurality of eventual consistency intent names corresponds to all eventual consistency intents of the dead session;

determine a subset of storage units responsible for storing the all eventual consistency intents of the dead session based on the prefix of the eventual consistency intent names in the subset;

retrieve the all eventual consistency intents of the dead session from the subset of storage units; and

facilitate execution of eventual consistency updates indicated in the all eventual consistency intents of the dead session.

12. The processing system of claim 11, wherein generating the subset of the plurality of eventual consistency intent names includes generating a prefixed-based listing of the plurality of eventual consistency intent names.

13. The processing system of claim 11, wherein the session identifier in the prefix of each of the plurality of eventual consistency intent names maps to the subset of storage units, and wherein the subset of storage units is determined based on the session identifier corresponding to the dead session included in the prefix.

14. The processing system of claim 13, wherein the all eventual consistency intents of the dead session are stored in subsets of storage units mapped to their session identifier corresponding to the dead session.

15. The processing system of claim 11, wherein the DSN includes a plurality of storage sets, and wherein the subset of storage units is located in a same one of the plurality of storage sets.

16. The processing system of claim 15, wherein each storage set includes a plurality of stripes of storage units, and wherein the subset of storage units is located in a same one of the plurality of storage stripes in the same one of the plurality of storage sets.

17. The processing system of claim 11, wherein the plurality of eventual consistency intent names is generated by utilizing a name generation scheme based on a weighted rendezvous strategy.

18. The processing system of claim 11, wherein the dead session is associated with a computing device of the DSN, and wherein the dead session is determined based on when the computing device crashing.

19. The processing system of claim 11, wherein the dead session is associated with a computing device of the DSN, and wherein the dead session is determined based on when the computing device encounters a network partition which prevents the computing device from accomplishing the eventual consistency update.

20. A non-transitory computer readable storage medium comprises:

at least one memory section that stores operational instructions that, when executed by a processing system of a dispersed storage network (DSN) that includes a processor and a memory, causes the processing system to;

determine a dead session of the DSN;

generate a subset of a plurality of eventual consistency intent names by identifying ones of the plurality of eventual consistency intent names that include a session identifier corresponding to the dead session in a prefix of the ones of the plurality of eventual consistency intent names, wherein the subset of the plurality of eventual consistency intent names corresponds to all eventual consistency intents of the dead session;

determine a subset of storage units responsible for storing the all eventual consistency intents of the dead session based on the prefix of the eventual consistency intent names in the subset;

retrieve the all eventual consistency intents of the dead session from the subset of storage units; and

facilitate execution of eventual consistency updates indicated in the all eventual consistency intents of the dead session.