Optimistic data writing in a dispersed storage network

• US 8,826,067 B2
• Filed: 10/24/2013
• Issued: 09/02/2014
• Est. Priority Date: 10/09/2007
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Cleversafe Incorporated (International Business Machines Corporation)
• Inventors: Dhuse, Greg
• Primary Examiner(s): KO, CHAE M
• Application Number:
  US14/062,478
• Publication Number:
  US 20140053018A1
• Time in Patent Office: 313 Days
• Field of Search: 714/6.24, 714/15, 714/18, 711/114
• US Class Current: 714/6.24
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 2211/1028 Distributed, i.e. distributed RAID systems with parity

Abstract

A method begins by a processing module dispersed storage error encoding data to produce a set of encoded data slices and sending a set of write request messages to a set of dispersed storage (DS) units, wherein each of the set of write request messages includes an encoded data slice of the set of encoded data slices. The method continues with the processing module determining whether a pillar width number of favorable write response messages has been received within a write acknowledgement (ACK) time period. The method continues with the processing module executing a retry write process to at least one DS unit of the set of DS units from which a favorable write response message was not received during the write ACK time period when the pillar width number of favorable write response messages has not been received within the write ACK time period.

Claims

1. A method for execution by a computer, the method comprises:

dispersed storage error encoding a data segment of data to produce a set of encoded data slices;

sending write request messages regarding the set of encoded data slices to dispersed storage (DS) units of a dispersed storage network;

receiving favorable write response messages from at least some of the DS units;

determining a number of favorable write response messages received within a write acknowledgement (ACK) time period; and

when the number of favorable write response messages is equal to or greater than a write threshold number but less than all for the set of encoded data slices;

sending write commit request messages to the at least some of the DS units; and

sending a retry write message for each encoded data slice of the set of encoded data slices for which a favorable write response message was not received within the write ACK time period.

2. The method of claim 1 further comprises at least one of:

sending the retry write message for each encoded data slice of the set of encoded data slices for which a favorable write response message was not received to each of the DS units that a favorable write response message was not received;

sending the retry write message for each encoded data slice of the set of encoded data slices for which a favorable write response message was not received to other DS units of the DSN memory; and

sending identify of each encoded data slice of the set of encoded data slices for which a favorable write response message was not received to a rebuilding module.

3. The method of claim 1 further comprises:

when the number of favorable write response messages is less than the write threshold number, executing a retry write process.

4. The method of claim 1 further comprises:

receiving favorable write commit response messages from at least some of the DS units;

determining a number of favorable write commit response messages received within a write commit acknowledgement (ACK) time period; and

when the number of favorable write commit response messages is equal to or greater than the write threshold number but less than all for the set of encoded data slices;

sending write finalize request messages to the at least some of the DS units; and

sending a retry write commit message for each encoded data slice of the set of encoded data slices for which a favorable write commit response message was not received within the write commit ACK time period.

5. The method of claim 4 further comprises:

when the number of favorable write commit response messages is less than the write threshold number;

executing a write commit retry process;

when the write commit retry process is unsuccessful, sending rollback messages to the DS units; and

when the write commit retry process is successful, sending write finalize request messages to the at least some of the DS units.

6. The method of claim 1 further comprises:

when the number of favorable write response messages equals the number of encoded data slices in the set of encoded data slices;

sending write commit request messages to the DS units;

receiving favorable write commit response messages from at least some of the DS units;

determining a number of favorable write commit response messages received within a write commit acknowledgement (ACK) time period; and

when the number of favorable write commit response messages equals the number of encoded data slices in the set of encoded data slices, sending write finalize request messages to the DS units.

7. A computer comprises:

an interface; and

a processing module operable to;

dispersed storage error encode a data segment of data to produce a set of encoded data slices;

send, via the interface, write request messages regarding the set of encoded data slices to dispersed storage (DS) units of a dispersed storage network;

receive, via the interface, favorable write response messages from at least some of the DS units;

determine a number of favorable write response messages received within a write acknowledgement (ACK) time period; and

when the number of favorable write response messages is equal to or greater than a write threshold number but less than all for the set of encoded data slices;

send, via the interface, write commit request messages to the at least some of the DS units; and

send, via the interface, a retry write message for each encoded data slice of the set of encoded data slices for which a favorable write response message was not received within the write ACK time period.

8. The computer of claim 7, wherein the processing module is further operable to perform at least one of:

send, via the interface, the retry write message for each encoded data slice of the set of encoded data slices for which a favorable write response message was not received to each of the DS units that a favorable write response message was not received;

send, via the interface, the retry write message for each encoded data slice of the set of encoded data slices for which a favorable write response message was not received to other DS units of the DSN memory; and

send, via the interface, identify of each encoded data slice of the set of encoded data slices for which a favorable write response message was not received to a rebuilding module.

9. The computer of claim 7, wherein the processing module is further operable to:

when the number of favorable write response messages is less than the write threshold number, execute a retry write process.

10. The computer of claim 7, wherein the processing module is further operable to:

receive, via the interface, favorable write commit response messages from at least some of the DS units;

determine a number of favorable write commit response messages received within a write commit acknowledgement (ACK) time period; and

when the number of favorable write commit response messages is equal to or greater than the write threshold number but less than all for the set of encoded data slices;

send, via the interface, write finalize request messages to the at least some of the DS units; and

send, via the interface, a retry write commit message for each encoded data slice of the set of encoded data slices for which a favorable write commit response message was not received within the write commit ACK time period.

11. The computer of claim 10, wherein the processing module is further operable to:

when the number of favorable write commit response messages is less than the write threshold number;

execute a write commit retry process;

when the write commit retry process is unsuccessful, send, via the interface, rollback messages to the DS units; and

when the write commit retry process is successful, send, via the interface, write finalize request messages to the at least some of the DS units.

12. The computer of claim 7, wherein the processing module is further operable to:

when the number of favorable write response messages equals the number of encoded data slices in the set of encoded data slices;

send, via the interface, write commit request messages to the DS units;

receive, via the interface, favorable write commit response messages from at least some of the DS units;

determine a number of favorable write commit response messages received within a write commit acknowledgement (ACK) time period; and

when the number of favorable write commit response messages equals the number of encoded data slices in the set of encoded data slices, send, via the interface write finalize request messages to the DS units.

13. A non-transitory machine-readable storage medium comprises:

a first section that stores operational instructions that, when executed by a computer, causes the computer to dispersed storage error encode a data segment of data to produce a set of encoded data slices;

a second section that stores operational instructions that, when executed by the computer, causes the computer to;

send, via a computer interface, write request messages regarding the set of encoded data slices to dispersed storage (DS) units of a dispersed storage network; and

receive, via the computer interface, favorable write response messages from at least some of the DS units;

a third section that stores operational instructions that, when executed by the computer, causes the computer to determine a number of favorable write response messages received within a write acknowledgement (ACK) time period; and

a fourth section that stores operational instructions that, when executed by the computer, causes the computer to, when the number of favorable write response messages is equal to or greater than a write threshold number but less than all for the set of encoded data slices;

send, via the computer interface, write commit request messages to the at least some of the DS units; and

send, via the computer interface, a retry write message for each encoded data slice of the set of encoded data slices for which a favorable write response message was not received within the write ACK time period.

14. The non-transitory machine-readable storage medium of claim 13, wherein the fourth section further comprises operational instructions that, when executed by the computer, causes the computer to perform at least one of:

send, via the computer interface, the retry write message for each encoded data slice of the set of encoded data slices for which a favorable write response message was not received to each of the DS units that a favorable write response message was not received;

send, via the computer interface, the retry write message for each encoded data slice of the set of encoded data slices for which a favorable write response message was not received to other DS units of the DSN memory; and

send, via the computer interface, identify of each encoded data slice of the set of encoded data slices for which a favorable write response message was not received to a rebuilding module.

15. The non-transitory machine-readable storage medium of claim 13 further comprises:

a fifth section that stores operational instructions that, when executed by the computer, causes the computer to execute a retry write process when the number of favorable write response messages is less than the write threshold number.

16. The non-transitory machine-readable storage medium of claim 13 further comprises:

a fifth section that stores operational instructions that, when executed by the computer, causes the computer to;

receive, via the computer interface, favorable write commit response messages from at least some of the DS units;

determine a number of favorable write commit response messages received within a write commit acknowledgement (ACK) time period; and

when the number of favorable write commit response messages is equal to or greater than the write threshold number but less than all for the set of encoded data slices;

send, via the computer interface, write finalize request messages to the at least some of the DS units; and

send, via the computer interface, a retry write commit message for each encoded data slice of the set of encoded data slices for which a favorable write commit response message was not received within the write commit ACK time period.

17. The non-transitory machine-readable storage medium of claim 16 further comprises:

the fifth section further stores operational instructions that, when executed by the computer, causes the computer to, when the number of favorable write commit response messages is less than the write threshold number;

execute a write commit retry process;

when the write commit retry process is unsuccessful, send, via the computer interface, rollback messages to the DS units; and

when the write commit retry process is successful, send, via the computer interface, write finalize request messages to the at least some of the DS units.

18. The non-transitory machine-readable storage medium of claim 13 further comprises:

a fifth section that stores operational instructions that, when executed by the computer, causes the computer to, when the number of favorable write response messages equals the number of encoded data slices in the set of encoded data slices;

send, via the computer interface, write commit request messages to the DS units;

receive, via the computer interface, favorable write commit response messages from at least some of the DS units;

determine a number of favorable write commit response messages received within a write commit acknowledgement (ACK) time period; and

when the number of favorable write commit response messages equals the number of encoded data slices in the set of encoded data slices, send, via the computer interface, write finalize request messages to the DS units.