Dynamically adjusting write requests for a multiple phase write operation

1. A method for execution by a computing device of a dispersed storage network (DSN), the method comprises:

for a current phase of a multiple phase write operation to write a set of encoded data slices to a set of storage units of the DSN, determining whether to send a write performance threshold number of write requests to a subset of the set of storage units regarding a write performance threshold number of encoded data slices of the set of encoded data slices, wherein a data segment of data is dispersed storage error encoded into the set of encoded data slices, wherein a write threshold number of favorable write responses is required to move to a next phase of the multiple phase write operation, wherein the set of encoded data slices includes a total number of encoded data slices, and wherein the write threshold number is less than the total number and greater than or equal to the write performance threshold number; and

when the determination is to send the write performance threshold number of write requests to the subset of the set of storage units, sending the write performance threshold number of write requests to the subset of the set of storage units.

2. The method of claim 1 further comprises:

when the determination is not to send the write performance threshold number of write requests to the subset of the set of storage units and the current phase is an initial phase of the multiple phase write operation, sending the total number of write requests to the set of storage units.

3. The method of claim 1 further comprises:

when the determination is not to send the write performance threshold number of write requests to the subset of the set of storage units and the current phase is a non-initial phase of the multiple phase write operation:

changing the write performance threshold number to produce a changed write performance threshold number; and

sending the changed write performance threshold number of write requests to a second subset of the set of storage units, wherein a number of the second subset of storage units is equal to the changed write performance threshold number.

4. The method of claim 1 further comprises:

receiving favorable responses to the write performance threshold number of write requests; and

when the write threshold number of favorable responses to the write performance threshold number of write requests have been received:

determining whether to change the write performance threshold number for a next phase of the multiple phase write operation; and

when the write performance threshold number is to be changed, changing the write performance threshold number to produce a changed write performance threshold number; and

sending the changed write performance threshold number of next phase write requests to a second subset of the set of storage units.

5. The method of claim 4 , wherein the determining whether to change the write performance threshold number comprises:

obtaining a set of current storage performance data regarding storage performance by the subset of storage units for the current phase of the multiple phase write operation;

interpreting the set of current storage performance data to identify one or more storage units having a less than a desired performance level; and

excluding the one or more storage units to produce the second subset of the set of storage units.

6. The method of claim 4 , wherein the determining whether to change the write performance threshold number comprises:

determining a number of unfavorable responses to the write performance threshold number of write requests; and

reducing the write performance threshold number by the number of unfavorable responses to produce the changed write performance threshold number.

7. The method of claim 1 , wherein the determining whether to send the write performance threshold number of write requests comprises:

obtaining a set of storage performance information regarding the set of storage units;

interpreting the set of storage performance information to identify one or more storage units having a less than a desired performance level, wherein a storage unit of the one or more storage units having the less than desired performance level adversely affects the multiple phase write operation; and

excluding the one or more storage units from the set of storage units to produce the subset of the set of storage units, wherein a number of the subset of the set of storage units is equal to the write performance threshold number.

8. The method of claim 1 , wherein a phase of the multiple phase write operation is one of:

a write initialize phase;

a write commit phase; and

a write finalize phase.

9. A computing device of a dispersed storage network (DSN) comprises:

an interface;

memory; and

a processing module operably coupled to the memory and the interface, wherein the processing module is operable to:

for a current phase of a multiple phase write operation to write a set of encoded data slices to a set of storage units of the DSN, determine whether to send a write performance threshold number of write requests to a subset of the set of storage units regarding a write performance threshold number of encoded data slices of the set of encoded data slices, wherein a data segment of data is dispersed storage error encoded into the set of encoded data slices, wherein a write threshold number of favorable write responses is required to move to a next phase of the multiple phase write operation, wherein the set of encoded data slices includes a total number of encoded data slices, and wherein the write threshold number is less than the total number and greater than or equal to the write threshold number; and

when the determination is to send the write performance threshold number of write requests to the subset of the set of storage units, send, via the interface, the write performance threshold number of write requests to the subset of the set of storage units.

10. The computing device of claim 9 , wherein the processing module is further operable to:

when the determination is not to send the write performance threshold number of write requests to the subset of the set of storage units and the current phase is an initial phase of the multiple phase write operation, send, via the interface, the total number of write requests to the set of storage units.

11. The computing device of claim 9 , wherein the processing module is further operable to:

when the determination is not to send the write performance threshold number of write requests to the subset of the set of storage units and the current phase is a non-initial phase of the multiple phase write operation:

change the write performance threshold number to produce a changed write performance threshold number; and

send, via the interface, the changed write performance threshold number of write requests to a second subset of the set of storage units, wherein a number of the second subset of storage units is equal to the changed write performance threshold number.

12. The computing device of claim 9 , wherein the processing module is further operable to:

receive favorable responses to the write performance threshold number of write requests; and

when the write threshold number of favorable responses to the write performance threshold number of write requests have been received:

determine whether to change the write performance threshold number for a next phase of the multiple phase write operation; and

when the write performance threshold number is to be changed, change the write performance threshold number to produce a changed write performance threshold number; and

send, via the interface, the changed write performance threshold number of next phase write requests to a second subset of the set of storage units.

13. The computing device of claim 12 , wherein the processing module is further operable to determine whether to change the write performance threshold number by:

obtaining a set of current storage performance data regarding storage performance by the subset of storage units for the current phase of the multiple phase write operation;

interpreting the set of current storage performance data to identify one or more storage units having a less than a desired performance level; and

excluding the one or more storage units to produce the second subset of the set of storage units.

14. The computing device of claim 12 , wherein the processing module is further operable to determine whether to change the write performance threshold number by:

determining a number of unfavorable responses to the write performance threshold number of write requests; and

reducing the write performance threshold number by the number of unfavorable responses to produce the changed write performance threshold number.

15. The computing device of claim 9 , wherein the processing module is further operable to determine whether to send the write performance threshold number of write requests by:

obtaining a set of storage performance information regarding the set of storage units;

interpreting the set of storage performance information to identify one or more storage units having a less than a desired performance level, wherein a storage unit of the one or more storage units having the less than desired performance level adversely affects the multiple phase write operation; and

excluding the one or more storage units from the set of storage units to produce the subset of the set of storage units, wherein a number of the subset of the set of storage units is equal to the write performance threshold number.

16. The computing device of claim 9 , wherein a phase of the multiple phase write operation is one of:

a write initialize phase;

a write commit phase; and

a write finalize phase.