Rotating offline DS units

1. A method comprises:

selectively, by a computing device of a dispersed storage network (DSN), bringing online and taking offline storage units of a set of storage units of the DSN;

when bringing a first storage unit of the set of storage units online and taking a second storage unit of the set of storage units offline in accordance with the selectively bringing online and taking offline storage units, determining, by the computing device, a rebuilding approach of the first storage unit and a first to second storage unit transition;

bringing, by the computing device, the first storage unit online in accordance with the rebuilding approach and the first to second storage unit transition; and

taking, by the computing device, the second storage unit offline in accordance with the first to second storage unit transition.

2. The method of claim 1 , wherein the selectively bringing online and taking offline storage units comprises one or more of:

a scheduled timeframe;

an amount of power consumed by a storage unit of the set of storage units;

an amount of data written to a storage unit of the set of storage units;

restricting taking offline a storage unit that includes an encoded data slice that needs rebuilding;

restricting taking offline a storage unit that includes an encoded data slice that is critical to a rebuilding of another encoded data slice; and

determining a storage unit of the set of storage units will not be available during a scheduled online timeframe.

3. The method of claim 1 , wherein the rebuilding approach comprises one or more of:

an expedited rebuilding procedure;

a normal rebuild procedure;

a full rebuilding technique; and

a partial rebuilding technique.

4. The method of claim 1 , wherein the first to second storage unit transition comprises one of:

keeping the second storage unit online;

taking the second storage unit offline after data of the first storage unit is rebuilt; and

taking the second storage offline once the first storage unit is online.

5. The method of claim 1 , wherein the determining the rebuilding approach and the first to second storage unit transition comprises one of:

determining one or more encoded data slices of the first storage unit needs to be rebuilt before the second storage unit goes offline when a number of online storage units is at or below a read threshold once the second storage unit is offline; and

determining one or more encoded data slices of the first storage unit does not need to be rebuilt before the second storage unit goes offline when the number of online storage units is at or above a write threshold once the second storage unit is offline.

6. The method of claim 1 further comprises:

when bringing the first storage unit and a third storage unit of the set of storage units online and taking the second storage unit and a fourth storage unit of the set of storage units offline, in accordance with the selectively bringing online and taking offline storage units, determining, by the computing device, a second rebuilding approach of the first and third storage units and a first and third to second and fourth storage unit transition;

bringing, by the computing device, the first and third storage units online in accordance with the second rebuilding approach and the first and third to second and fourth storage unit transition; and

taking, by the computing device, the second and fourth storage units offline in accordance with the first and third to second and fourth storage unit transition.

7. The method of claim 6 further comprises:

concurrently rebuilding, according to the second rebuilding approach and the third to second and fourth storage unit transition, one or more sets of encoded data slices of the first and third storage units that need rebuilding.

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

memory;

an interface; and

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

selectively bring online and take offline storage units of a set of storage units of the DSN;

when bringing a first storage unit of the set of storage units online and taking a second storage unit of the set of storage units offline in accordance with the selectively bringing online and taking offline storage units, determine a rebuilding approach of the first storage unit and a first to second storage unit transition;

bring the first storage unit online in accordance with the rebuilding approach and the first to second storage unit transition; and

take the second storage unit offline in accordance with the first to second storage unit transition.

9. The computing device of claim 8 , wherein the processing module is operable to selectively bring online and take offline storage units according to one or more of:

a scheduled timeframe;

an amount of power consumed by a storage unit of the set of storage units;

an amount of data written to a storage unit of the set of storage units;

restricting taking offline a storage unit that includes an encoded data slice that needs rebuilding;

restricting taking offline a storage unit that includes an encoded data slice that is critical to a rebuilding of another encoded data slice; and

determining a storage unit of the set of storage units will not be available during a scheduled online timeframe.

10. The computing device of claim 8 , wherein the processing module is operable to perform the rebuilding approach by one or more of:

an expedited rebuilding procedure;

a normal rebuild procedure;

a full rebuilding technique; and

a partial rebuilding technique.

11. The computing device of claim 8 , wherein the processing module is operable to perform the first to second storage unit transition by one of:

keeping the second storage unit online;

taking the second storage unit offline after data of the first storage unit is rebuilt; and

taking the second storage offline once the first storage unit is online.

12. The computing device of claim 8 , wherein the processing module is operable to determine the rebuilding approach and the first to second storage unit transition by one of:

determining data within the first storage unit needs to be rebuilt before the second storage unit goes offline when a number of online storage units is at or below a read threshold once the second storage unit is offline; and

determining data within the first storage unit does not need to be rebuilt before the second storage unit goes offline when the number of online storage units is at or above a write threshold once the second storage unit is offline.

13. The computing device of claim 8 , wherein the processing module is further operable to:

when bringing the first storage unit and a third storage unit of the set of storage units online and taking the second storage unit and a fourth storage unit of the set of storage units offline, in accordance with the selectively bringing online and taking offline storage units, determine, a second rebuilding approach of the first and third storage units and a first and third to second and fourth storage unit transition;

bring the first and third storage units online in accordance with the second rebuilding approach and the first and third to second and fourth storage unit transition; and

take the second and fourth storage units offline in accordance with the first and third to second and fourth storage unit transition.

14. The computing device of claim 13 , wherein the processing module is further operable to:

concurrently rebuild, according to the second rebuilding approach and the third to second and fourth storage unit transition, one or more sets of encoded data slices of the first and third storage units that need rebuilding.