Revision synchronization of a dispersed storage network

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 a revision number of the DS unit most-recent slice revision is same as a revision number of 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 revision number of the DS unit most-recent slice revision is not the same as the revision number of the DS processing module most-recent slice revision:

generating a write response message to include a condition status code indicating an unfavorable comparison of the revision numbers; 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 identifier associated with the encoded directory slice is different than 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 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 a revision number of the DS unit most-recent slice revision is same as a revision number of 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.

7. The DS unit of claim 6 , 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.

8. The DS unit of claim 6 , wherein the processing module further functions to:

when the revision number of the DS unit most-recent slice revision is not the same as the revision number of the DS processing module most-recent slice revision:

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

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

9. The DS unit of claim 6 , 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 identifier associated with the encoded directory slice is different than 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.

10. The DS unit of claim 9 , 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.