Selecting retrieval locations in a dispersed storage network

A processing system of a dispersed storage and task (DST) processing 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 to recover a data segment from a set of storage units;
• identify a plurality of candidate retrieval locations of the set of storage units;
• obtain performance information for each of the plurality of candidate retrieval locations;
• identify a plurality of permutations of the plurality of candidate retrieval locations, wherein each of the plurality of permutations corresponds to a proper subset of the plurality of candidate retrieval locations that includes a number of candidate retrieval locations selected from the plurality of candidate retrieval locations, wherein the number is strictly less than a total number of candidate retrieval locations in the plurality of candidate retrieval locations, and wherein the number is strictly greater than a decode threshold number;
• determine a cost-benefit level for each of the plurality of permutations of of the candidate retrieval locations based on the performance information;
• select one of the plurality of permutations based on the cost-benefit level for each of the plurality of permutations;
• send, via a network, read slice requests to ones of the plurality of candidate retrieval locations included in the one of the plurality of permutations;
• receive, via the network, a plurality of encoded data slices from the ones of the plurality of candidate retrieval locations in response to the read slice requests;
• and
• reproduce the data segment in response to the plurality of encoded data slices including the decode threshold number of encoded data slices.

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 to recover a data segment from a set of storage units;
• identify a plurality of candidate retrieval locations of the set of storage units;
• obtain performance information for each of the plurality of candidate retrieval locations;
• identify a plurality of permutations of the plurality of candidate retrieval locations, wherein each of the plurality of permutations corresponds to a proper subset of the plurality of candidate retrieval locations that includes a number of candidate retrieval locations selected from the plurality of candidate retrieval locations, wherein the number is strictly less than a total number of candidate retrieval locations in the plurality of candidate retrieval locations, and wherein the number is strictly greater than a decode threshold number;
• determine a cost-benefit level for each of the plurality of permutations of of the candidate retrieval locations based on the performance information;
• select one of the plurality of permutations based on the cost-benefit level for each of the plurality of permutations;
• send, via a network, read slice requests to ones of the plurality of candidate retrieval locations included in the one of the plurality of permutations;
• receive, via the network, a plurality of encoded data slices from the ones of the plurality of candidate retrieval locations in response to the read slice requests;
• and
• reproduce the data segment in response to the plurality of encoded data slices including the decode threshold number of encoded data slices.