Minimizing data movement through rotation of spare memory devices

1. A method for use in a distributed storage network (DSN) including a plurality of distributed storage task execution (DST EX) units, each of the plurality of DST EX units including a plurality of distributed storage (DS) memories configured to store encoded data slices, the method comprising:

detecting, by a DST EX unit including a processor and associated memory, a physical storage failure associated with a first DS memory included in the DST EX unit, wherein the first DS memory is associated with a sub-DSN address range;

selecting an available spare DS memory included in the DST EX unit;

updating slice mapping information to associate the available spare DS memory with the sub-DSN address range;

facilitating, by the DST EX unit, rebuilding one or more encoded data slices associated with the sub-DSN address range to produce one or more rebuilt encoded data slices; and

facilitating, by the DST EX unit, storing the one or more rebuilt encoded data slices in the available spare DS memory.

2. The method of claim 1 , further comprising:

after storing the one or more rebuilt encoded data slices in the available spare DS memory, maintaining the first DS memory as a spare DS memory until a physical storage failure associated with a second DS memory is detected.

3. The method of claim 1 , further comprising:

choosing the available spare DS memory from a plurality of available spare DS memories based on one or more of a capacity level, an estimated performance level, or a compatibility factor.

4. The method of claim 1 , further comprising:

updating slice mapping information by updating a local table that includes the slice mapping information to:

associate the sub-DSN address range with the available spare DS memory; and

disassociate the sub-DSN address range from the first DS memory.

5. The method of claim 1 , further comprising:

locally rebuilding the one or more encoded data slices, by the DST EX unit, to generate one or more rebuilt encoded data slices.

6. The method of claim 5 , wherein locally rebuilding includes:

obtaining a decode threshold number of slice representations of a set of encoded data slices that includes an encoded data slice for rebuilding;

decoding the decode threshold number of slice representations to reproduce a data segment; and

encoding the data segment to generate the one or more rebuilt encoded data slices.

7. The method of claim 1 , further comprising:

issuing a rebuild request to a rebuilding agent, the rebuild request including instructions to the rebuilding agent to send rebuilt encoded data slices to the DST EX unit;

receiving, at the DST EX unit, one or more rebuilt data slices from the rebuilding agent; and

storing the one or more rebuilt data slices in the available spare DS memory.

8. A distributed storage task execution (DST EX) unit for use in a distributed storage network (DSN), the DST EX unit comprising:

a processor and associated memory;

a plurality of distributed storage (DS) memories coupled to the processor and associated memory, the plurality of DS memories configured to store encoded data slices;

the processor and associated memory configured to:

detect a physical storage failure associated with a first DS memory, wherein the first DS memory is associated with a sub-DSN address range;

select an available spare DS memory from the plurality of DS memories;

update slice mapping information to associate the available spare DS memory with the sub-DSN address range;

facilitate rebuilding one or more encoded data slices associated with the sub-DSN address range to produce one or more rebuilt encoded data slices; and

facilitate storing the one or more rebuilt encoded data slices in the available spare DS memory.

9. The distributed storage task execution (DST EX) unit of claim 8 , the processor and associated memory further configured to:

after storing the one or more rebuilt encoded data slices in the available spare DS memory, maintain the first DS memory as a spare DS memory until a physical storage failure associated with a second DS memory is detected.

10. The distributed storage task execution (DST EX) unit of claim 8 , the processor and associated memory further configured to:

choose the available spare DS memory from a plurality of available spare DS memories based on one or more of a capacity level, an estimated performance level, or a compatibility factor.

11. The distributed storage task execution (DST EX) unit of claim 8 , the processor and associated memory further configured to:

update a local table including slice mapping information to:

associate the sub-DSN address range with the available spare DS memory; and

disassociate the sub-DSN address range from the first DS memory.

12. The distributed storage task execution (DST EX) unit of claim 8 , the processor and associated memory further configured to:

locally rebuild the one or more encoded data slices to generate one or more rebuilt encoded data slices.

13. The distributed storage task execution (DST EX) unit of claim 12 , the processor and associated memory further configured to:

obtain a decode threshold number of slice representations of a set of encoded data slices that includes an encoded data slice for rebuilding;

decode the decode threshold number of slice representations to reproduce a data segment; and

encode the data segment to generate the one or more rebuilt encoded data slices.

14. The distributed storage task execution (DST EX) unit of claim 8 , the processor and associated memory further configured to:

issue a rebuild request to a rebuilding agent, the rebuild request including instructions to the rebuilding agent to send rebuilt encoded data slices to the DST EX unit;

receive one or more rebuilt data slices from the rebuilding agent; and

store the one or more rebuilt data slices in the available spare DS memory.

15. A distributed storage network (DSN) comprising:

a set of distributed storage task execution (DST EX) units, at least one DST EX unit included in the set of DST EX units including:

a processor and associated memory;

a plurality of distributed storage (DS) memories coupled to the processor and associated memory, the plurality of DS memories configured to store encoded data slices;

the processor and associated memory configured to:

detect a physical storage failure associated with a first DS memory, wherein the first DS memory is associated with a sub-DSN address range;

select an available spare DS memory from the plurality of DS memories;

update slice mapping information to associate the available spare DS memory with the sub-DSN address range;

facilitate rebuilding one or more encoded data slices associated with the sub-DSN address range to produce one or more rebuilt encoded data slices; and

facilitate storing the one or more rebuilt encoded data slices in the available spare DS memory.

16. The distributed storage network (DSN) of claim 15 , the processor and associated memory further configured to:

after storing the one or more rebuilt encoded data slices in the available spare DS memory, maintain the first DS memory as a spare DS memory until a physical storage failure associated with a second DS memory is detected.

17. The distributed storage network (DSN) of claim 15 , the processor and associated memory further configured to:

choose the available spare DS memory from a plurality of available spare DS memories based on one or more of a capacity level, an estimated performance level, or a compatibility factor.

18. The distributed storage network (DSN) of claim 15 , the processor and associated memory further configured to:

update a local table including slice mapping information to:

associate the sub-DSN address range with the available spare DS memory; and

disassociate the sub-DSN address range from the first DS memory.

19. The distributed storage network (DSN) of claim 15 , the processor and associated memory further configured to:

locally rebuild the one or more encoded data slices to generate one or more rebuilt encoded data slices, wherein locally rebuilding includes:

obtaining a decode threshold number of slice representations of a set of encoded data slices that includes an encoded data slice for rebuilding;

decoding the decode threshold number of slice representations to reproduce a data segment; and

encoding the data segment to generate the one or more rebuilt encoded data slices.

20. The distributed storage network (DSN) of claim 15 , further including:

a rebuilding module coupled to the at least one DST EX unit, the rebuilding module configured to rebuild encoded data slices on behalf of the at least one DST EX unit;

the processor and associated memory further configured to:

issue a rebuild request to a rebuilding agent, the rebuild request including instructions to the rebuilding agent to send rebuilt encoded data slices to the DST EX unit;

receive one or more rebuilt data slices from the rebuilding agent; and

store the one or more rebuilt data slices in the available spare DS memory.