REVISION SYNCHRONIZATION OF A DISPERSED STORAGE NETWORK

• US 20110161754A1
• Filed: 10/13/2010
• Published: 06/30/2011
• Est. Priority Date: 12/29/2009
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Cleversafe Incorporated (International Business Machines Corporation)
• Inventors: LEGGETTE, WESLEY, RESCH, JASON K., VOLVOVSKI, ILYA, BAPTIST, ANDREW, DHUSE, GREG, CILFONE, BART
• Granted Patent: US 9,152,489 B2
• Time in Patent Office: Days
• US Class Current: 714/718
• CPC Class Codes: G06F 11/0745 in an input/output transactions management context input/output processing in general G06F13/00
• CPC Class Codes: G06F 11/1064 in cache or content addressable memories
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G06F 11/1443 Transmit or communication errors
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 12/0813 with a network or matrix configuration
• CPC Class Codes: G06F 12/0815 Cache consistency protocols
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: G06F 2211/1028 Distributed, i.e. distributed RAID systems with parity
• CPC Class Codes: G06F 2211/1057 Parity-multiple bits-RAID6, i.e. RAID 6 implementations
• CPC Class Codes: G06F 9/467 Transactional memory G06F9/528 takes precedence

Abstract

A method begins by a processing module receiving a write request message from a dispersed storage (DS) processing module, wherein the write request message includes a slice name, a DS processing module most-recent slice revision, a new slice revision, and an encoded directory slice of directory information regarding storage of data. The method continues with the processing module obtaining, from local memory, a DS unit most-recent slice revision based on the slice name. The method continues with the processing module storing the new slice revision as the DS unit most-recent slice revision and storing the encoded directory slice when the DS unit most-recent slice revision compares favorably to the DS processing module most-recent slice revision.

Claims

1. A method for execution by a dispersed storage (DS) unit, the method comprises:

receiving a write request message from a dispersed storage (DS) processing module, wherein the write request message includes a slice name, a DS processing module most-recent slice revision, a new slice revision, and an encoded directory slice of directory information regarding storage of data;

obtaining, from local memory, a DS unit most-recent slice revision based on the slice name; and

when the DS unit most-recent slice revision compares favorably to the DS processing module most-recent slice revision;

storing the new slice revision as the DS unit most-recent slice revision; and

storing the encoded directory slice.

2. The method of claim 1 further comprises:

generating a write response message that includes an operation succeeded status code; and

sending the write response message to the DS processing module.

3. The method of claim 1 further comprises:

when the DS unit most-recent slice revision compares unfavorably to the DS processing module most-recent slice revision;

generating a write response message to include a condition status code indicating the unfavorable comparison; and

sending the write response message to the DS processing module.

4. The method of claim 1 further comprises:

receiving the write request message, wherein the write request message further includes a DS processing module transaction identifier;

determining whether the slice name has a locked state based on a local state indicator; and

when the slice name has the locked state and a DS unit transaction indicator associated with the encoded directory slice compares unfavorably to the DS processing module transaction identifier;

generating a write response message that includes a transaction conflict status code; and

sending the write response message to the DS processing module.

5. The method of claim 4 further comprises:

when the slice name does not have a locked state;

updating the local state indicator to indicate that the slice name has the locked state; and

storing the DS processing module transaction identifier as the DS unit transaction identifier.

6. A method for execution by a dispersed storage (DS) unit, the method comprises:

receiving a commit transaction request message regarding storage of at least one of an encoded data slice and an encoded directory slice, wherein the commit transaction request message includes at least one transaction identifier;

identifying one or more slice names based on the at least one transaction identifier; and

for each of the one or more slices names, updating a slice status indicator to indicate the at least one of the encoded data slice and the encoded directory slice is visible.

7. The method of claim 6 further comprises:

the commit transaction request message includes first and second transaction identifiers of the at least one transaction identifier, wherein the first transaction identifier is associated with the encoded data slice and the second transaction identifier is associated with the encoded directory slice;

updating a first slice status indicator to indicate that the encoded data slice is visible; and

updating a second slice status indicator to indicate that the encoded directory slice is visible.

8. The method of claim 6 further comprises:

the commit transaction request message includes first and second transaction identifiers of the at least one transaction identifier, wherein the first transaction identifier is associated with the encoded data slice and the second transaction identifier is associated with the encoded directory slice;

re-updating a first slice status indicator to indicate that the encoded data slice is not visible when a DS unit memory error exists; and

re-updating a second slice status indicator to indicate that the encoded directory slice is not visible when the DS unit memory error exists.

9. The method of claim 6 further comprises:

updating a current revision indicator associated with the slice name and transaction identifier to indicate a revision associated with the slice name.

10. The method of claim 6 further comprises:

updating the slice status indicator to indicate that the slice name has an unlocked state subsequent to indicating that the at least one of the encoded data slice and the encoded directory slice is visible.

11. A dispersed storage (DS) unit comprises:

an interface;

a local memory; and

a processing module operable to;

receive, via the interface, a write request message from a dispersed storage (DS) processing module, wherein the write request message includes a slice name, a DS processing module most-recent slice revision, a new slice revision, and an encoded directory slice of directory information regarding storage of data;

obtain, from the local memory, a DS unit most-recent slice revision based on the slice name; and

when the DS unit most-recent slice revision compares favorably to the DS processing module most-recent slice revision;

store, in the local memory, the new slice revision as the DS unit most-recent slice revision; and

store, in the local memory, the encoded directory slice.

12. The computer of claim 11, wherein the processing module further functions to:

generate a write response message that includes an operation succeeded status code; and

send, via the interface, the write response message to the DS processing module.

13. The computer of claim 11, wherein the processing module further functions to:

when the DS unit most-recent slice revision compares unfavorably to the DS processing module most-recent slice revision;

generate a write response message to include a condition status code indicating the unfavorable comparison; and

send, via the interface, the write response message to the DS processing module.

14. The computer of claim 11, wherein the processing module further functions to:

receive, via the interface, the write request message, wherein the write request message further includes a DS processing module transaction identifier;

determine whether the slice name has a locked state based on a local state indicator; and

when the slice name has the locked state and a DS unit transaction indicator associated with the encoded directory slice compares unfavorably to the DS processing module transaction identifier;

generate a write response message that includes a transaction conflict status code; and

send, via the interface, the write response message to the DS processing module.

15. The computer of claim 14, wherein the processing module further functions to:

when the slice name does not have a locked state;

update, in the local memory, the local state indicator to indicate that the slice name has the locked state; and

store, in the local memory, the DS processing module transaction identifier as the DS unit transaction identifier.

16. A dispersed storage (DS) unit comprises:

an interface;

a local memory; and

a processing module operable to;

receive, via the interface, a commit transaction request message regarding storage of at least one of an encoded data slice and an encoded directory slice, wherein the commit transaction request message includes at least one transaction identifier;

identify one or more slice names based on the at least one transaction identifier; and

for each of the one or more slices names, update a slice status indicator, in the local memory, to indicate the at least one of the encoded data slice and the encoded directory slice is visible.

17. The computer of claim 16, wherein the processing module further functions to:

the commit transaction request message includes first and second transaction identifiers of the at least one transaction identifier, wherein the first transaction identifier is associated with the encoded data slice and the second transaction identifier is associated with the encoded directory slice;

update, in the local memory, a first slice status indicator to indicate that the encoded data slice is visible; and

update, in the local memory, a second slice status indicator to indicate that the encoded directory slice is visible.

18. The computer of claim 16, wherein the processing module further functions to:

the commit transaction request message includes first and second transaction identifiers of the at least one transaction identifier, wherein the first transaction identifier is associated with the encoded data slice and the second transaction identifier is associated with the encoded directory slice;

re-update, in the local memory, a first slice status indicator to indicate that the encoded data slice is not visible when a DS unit memory error exists; and

re-update, in the local memory, a second slice status indicator to indicate that the encoded directory slice is not visible when the DS unit memory error exists.

19. The computer of claim 16, wherein the processing module further functions to:

update, in the local memory, a current revision indicator associated with the slice name and transaction identifier to indicate a revision associated with the slice name.

20. The computer of claim 16, wherein the processing module further functions to:

update, in the local memory, the slice status indicator to indicate that the slice name has an unlocked state subsequent to indicating that the at least one of the encoded data slice and the encoded directory slice is visible.