Optimizing rebuilds when using multiple information dispersal algorithms

1. A method for execution by one or more processing modules of one or more computing devices of a dispersed storage network (DSN), the DSN storing a first set of encoded data slices and a second set of encoded data slices, wherein a data segment is dispersed storage error encoded using first dispersal parameters and differing second dispersal parameters to produce, respectively, the first and second sets of encoded data slices, the method comprising:

identifying a storage error associated with storage in the DSN of a first encoded data slice of the first set of encoded data slices;

in response to identifying the storage error, determining that a first decode threshold number associated with the first dispersal parameters is greater than a second decode threshold number associated with the second dispersal parameters;

obtaining, from storage of the DSN, a second decode threshold number of encoded data slices of the second set of encoded data slices;

generating, by the one or more processing modules, a rebuilt encoded data slice associated with the first encoded data slice using the second decode threshold number of encoded data slices; and

storing the rebuilt encoded data slice associated with the first encoded data slice.

2. The method of claim 1 , wherein the first set of encoded data slices is stored in a first set of dispersed storage units and the second set of encoded data slices is stored in a second set of dispersed storage units.

3. The method of claim 2 , wherein the first set of dispersed storage units include a first number of dispersed storage units corresponding to a first information dispersal algorithm width number of the first dispersal parameters and the second set of dispersed storage units include a second number of dispersed storage units corresponding to a second information dispersal algorithm width number of the second dispersal parameters.

4. The method of claim 3 , wherein the first information dispersal algorithm width number of the first dispersal parameters is greater than the first decode threshold number and the second information dispersal algorithm width number of the second dispersal parameters is greater than the second decode threshold number.

5. The method of claim 3 , wherein generating a rebuilt encoded data slice associated with the first encoded data slice using the second decode threshold number of encoded data slices further comprises dispersed storage error decoding, by the one or more processing modules, the second decode threshold number of encoded data slices using the second dispersal parameters to produce a recovered data segment.

6. The method of claim 5 , further comprising dispersed storage error encoding, by the one or more processing modules, the recovered data segment using the first dispersal parameters.

7. The method of claim 1 , wherein identifying a storage error associated with a first encoded data slice of a first set of encoded data slices further comprises interpreting list slice responses, interpreting an error message and interpreting a read slice response.

8. The method of claim 1 , further comprising issuing, by the one or more processing modules, read slice requests for the second decode threshold number of encoded data slices.

9. The method of claim 1 , wherein storing the rebuilt encoded data slice associated with the first encoded data slice further comprises identifying, by the one or more processing modules, a storage unit associated with the storage error and identifying another storage unit with favorable capacity and performance for storage of the rebuilt encoded data slice.

10. A dispersed storage integrity processing unit for use in a dispersed storage network, the dispersed storage network including a first set of dispersed storage units storing a first set of encoded data slices and a second set of dispersed storage units storing a second set of encoded data slices, wherein a data segment is dispersed storage error encoded using first dispersal parameters and differing second dispersal parameters to produce, respectively, the first and second sets of encoded data slices, the dispersed storage integrity processing unit comprising:

a communications interface;

a memory; and

a computer processor;

where the memory includes instructions for causing the computer processor to:

identify a storage error associated with a first encoded data slice of the first set of encoded data slices;

in response to identifying the storage error, determine that a first decode threshold number associated with the first dispersal parameters is greater than a second decode threshold number associated with the second dispersal parameters;

obtain, via the communications interface, a second decode threshold number of second encoded data slices of the second set of encoded data slices;

generate a rebuilt encoded data slice associated with the first encoded data slice using the second decode threshold number of second encoded data slices; and

issue, via the communications interface, a write slice request to store the rebuilt encoded data slice associated with the first encoded data slice.

11. The dispersed storage integrity processing unit of claim 10 , wherein the first set of encoded data slices is stored in a first information dispersal algorithm width number of the first set of dispersed storage units and the second set of encoded data slices is stored in a second information dispersal algorithm width number of the second set of dispersed storage units.

12. The dispersed storage integrity processing unit of claim 11 , wherein the first information dispersal algorithm width number is greater than the first decode threshold number and the second information dispersal algorithm width number is greater than the second decode threshold number.

13. The dispersed storage integrity processing unit of claim 12 , wherein the first information dispersal algorithm width number is greater than the second information dispersal algorithm width number.

14. The dispersed storage integrity processing unit of claim 12 , wherein the memory further comprises instructions for causing the computer processor to dispersed storage error decode the second decode threshold number of second encoded data slices using the second dispersal parameters to produce a recovered data segment.

15. The dispersed storage integrity processing unit of claim 14 , wherein the memory further comprises instructions for causing the computer processor to dispersed storage error encode the recovered data segment using the first dispersal parameters.

16. The dispersed storage integrity processing unit of claim 10 , wherein the memory further comprises instructions for causing the computer processor to interpret list slice responses, interpret an error message and interpret a read slice response.

17. The dispersed storage integrity processing unit of claim 10 , wherein the memory further comprises instructions for causing the computer processor to issue read slice requests for the second decode threshold number of second encoded data slices.

18. The dispersed storage integrity processing unit of claim 10 , wherein the memory further comprises instructions for causing the computer processor to identify a storage unit associated with the storage error and identify another storage unit with favorable capacity and performance.

19. A dispersed storage network comprising:

a first set of dispersed storage units storing a first set of encoded data slices, wherein a data segment is dispersed storage error encoded using first dispersal parameters to produce the first set of encoded data slices;

a second set of dispersed storage units storing a second set of encoded data slices, wherein the data segment is dispersed storage error encoded using second dispersal parameters to produce the second set of encoded data slices; and

a disperse storage integrity processing unit including:

a communications interface;

a memory; and

a computer processor;

where the memory includes instructions for causing the computer processor to:

identify a storage error associated with a first encoded data slice of the first set of encoded data slices;

determine that a first decode threshold number associated with the first dispersal parameters is greater than a second decode threshold number associated with the second dispersal parameters;

obtain, via the communications interface, a second decode threshold number of second encoded data slices of the second set of encoded data slices;

generate a rebuilt encoded data slice associated with the first encoded data slice using the second decode threshold number of second encoded data slices; and

store the rebuilt encoded data slice associated with the first encoded data slice.

20. The dispersed storage network of claim 19 , wherein the first set of encoded data slices is stored in a subset of the first set of dispersed storage units and the second set of encoded data slices is stored in a subset of the second set of dispersed storage units.