Rotating offline storage units in a dispersed storage network

1 . A method comprises:

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

when bringing a first storage unit of the set of storage units online in accordance with the selectively bringing online and taking offline storage units, determining, by the computing device, a rebuilding approach for data stored or to be stored in the first storage unit; and

bringing, by the computing device, the first storage unit online in accordance with the rebuilding approach.

2 . The method of claim 1 further comprises:

when 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 a first to second storage unit transition;

bringing, by the computing device, the first storage unit online in accordance with 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.

3 . The method of claim 2 , 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.

4 . The method of claim 2 , wherein the determining 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.

5 . The method of claim 1 further comprises:

prior to bringing, by the computing device, the first storage unit online:

determining, during a write request, the first storage unit of the set of storage units is offline;

determining to store encoded data slices of the write request to be stored in the first storage unit in another storage unit of the set of storage units; and

determining the rebuilding approach for the encoded data slices includes transferring storage of the encoded data slices stored from the other storage unit to the first storage unit.

6 . 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.

7 . 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, 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

bringing, by the computing device, the first and third storage units online in accordance with the second rebuilding approach.

8 . The method of claim 7 further comprises:

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

9 . 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:

rotate offline storage units of a set of storage units of the DSN by selectively bringing online and taking offline storage units of the set of storage units, 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;

when bringing a first storage unit of the set of storage units online in accordance with the selectively bringing online and taking offline storage units, determine a rebuilding approach for data stored or to be stored in the first storage unit; and

bring the first storage unit online in accordance with the rebuilding approach.

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

when 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 first to second storage unit transition;

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

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

11 . The computing device of claim 10 , wherein the processing module is operable to determine 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.

12 . The computing device of claim 10 , wherein the processing module is operable to determine 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.

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

prior to bringing the first storage unit online:

determine, during a write request, the first storage unit of the set of storage units is offline;

determine to store encoded data slices of the write request to be stored in the first storage unit in another storage unit of the set of storage units; and

determine the rebuilding approach for the encoded data slices includes transferring storage of the encoded data slices stored from the other storage unit to the first storage unit.

14 . The computing device of claim 9 , wherein the processing module is operable to determine 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.

15 . The computing device of claim 9 , 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, 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

bring the first and third storage units online in accordance with the second rebuilding approach.

16 . The computing device of claim 15 , wherein the processing module is further operable to:

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