Policy-based access in a dispersed storage network

1. A method comprises:

receiving from a requester, by a computing device of a dispersed storage network (DSN), a read request regarding a set of encoded data slices stored in a set of storage units of the DSN, wherein a data segment of data is dispersed storage error encoded to produce the set of encoded data slices;

obtaining, by the computing device, an access policy for the read request, wherein the access policy includes time varying availability patterns for the set of storage units, wherein less than a decode threshold number of storage units of the set of storage units are available for read requests during any one time varying availability pattern of the time varying availability patterns;

retrieving from a first group of storage units of the set of storage units, by the computing device and during a first time varying availability pattern of the time varying availability patterns, first encoded data slices of the set of encoded data slices available in the first time varying availability pattern;

retrieving from a second group of storage units the set of storage units, by the computing device and during a second time varying availability pattern of the time varying availability patterns, second encoded data slices of the set of encoded data slices available in the second time varying availability pattern;

determining, by the computing device based on a number of the first and second encoded data slices retrieved from the first and second groups of storage units, whether the decode threshold number of encoded data slices of the set of encoded data slices has been retrieved; and

when the decode threshold number of encoded data slices has been retrieved:

decoding, by the computing device, the decode threshold number of encoded data slices to recover the data segment.

2. The method of claim 1 further comprises:

when the decode threshold number of encoded data slices has not been retrieved, continuing the retrieving in accordance with the time varying availability patterns by:

retrieving from a third group of storage units of the set of storage units, by the computing device and during a third time varying availability pattern of the time varying availability patterns, third encoded data slices of the set of encoded data slices.

3. The method of claim 2 further comprises:

determining, by the computing device based on a second number of the first, second and third encoded data slices retrieved from the first, second, and third groups of storage units, whether the decode threshold number of the encoded data slices has been retrieved; and

when the decode threshold number of encoded data slices has been retrieved:

decoding, by the computing device, the first, second and third encoded data slices to recover the data segment.

4. The method of claim 1 , wherein the read request includes one or more of: a requester identifier (ID), a command, an access policy update, a data object ID, a source name, a data type, a data size indicator, a priority indicator, a security indicator, or a performance indicator.

5. The method of claim 1 , wherein the obtaining the access policy for the read request includes obtaining one or more of: a previously received access policy, a requester ID, a command, an access policy update, a data object ID, a source name, a data type, a data size indicator, a priority indicator, a security indicator, or a performance indicator.

6. The method of claim 1 , wherein the obtaining the access policy to apply to the read request is based on a stored access policy associated with at least one slice name of the set of encoded data slices.

7. The method of claim 1 further comprises:

sending an unavailable message to the requester when the set of encoded data slices is unable to be retrieved after a number of time varying availability patterns.

8. The method of claim 1 , wherein the requester is at least one of: a user device, a dispersed storage (DS) processing unit, a storage integrity processing unit, and a managing unit.

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

an interface;

a memory; and

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

receive from a requester, via the interface, a read request regarding a set of encoded data slices stored in a set of storage units of the DSN, wherein a data segment of data is dispersed storage error encoded to produce the set of encoded data slices;

obtain an access policy for the read request, wherein the access policy includes time varying availability patterns for the set of storage units, wherein less than a decode threshold number of storage units of the set of storage units are available for read requests during any one time varying availability pattern of the time varying availability patterns;

retrieve from a first group of storage units of the set of storage units, during a first time varying availability pattern of the time varying availability patterns, first encoded data slices of the set of encoded data slices available in the first time varying availability pattern;

retrieve from a second group of storage units the set of storage units, during a second time varying availability pattern of the time varying availability patterns, second encoded data slices of the set of encoded data slices available in the second time varying availability pattern;

determine, based on a number of the first and second encoded data slices retrieved from the first and second groups of storage units, whether the decode threshold number of encoded data slices of the set of encoded data slices has been retrieved; and

when the decode threshold number of encoded data slices has been retrieved:

decode the decode threshold number of encoded data slices to recover the data segment.

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

when the decode threshold number of encoded data slices has not been retrieved, continue the retrieving in accordance with the time varying availability patterns by:

retrieving from a third group of storage units of the set of storage units, by the computing device and during a third time varying availability pattern of the time varying availability patterns, third encoded data slices of the set of encoded data slices.

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

determine, based on a second number of the first, second and third encoded data slices retrieved from the first, second, and third groups of storage units, whether the decode threshold number of the encoded data slices has been retrieved; and

when the decode threshold number of encoded data slices has been retrieved:

decode the first, second and third encoded data slices to recover the data segment.

12. The computing device of claim 9 , wherein the read request includes one or more of: a requester identifier (ID), a command, an access policy update, a data object ID, a source name, a data type, a data size indicator, a priority indicator, a security indicator, or a performance indicator.

13. The computing device of claim 9 , wherein the processing module is operable to obtain the access policy for the read request by obtaining one or more of: a previously received access policy, a requester ID, a command, an access policy update, a data object ID, a source name, a data type, a data size indicator, a priority indicator, a security indicator, or a performance indicator.

14. The computing device of claim 9 , wherein the processing module is operable to obtain the access policy to apply to the read request by obtaining a stored access policy associated with at least one slice name of the set of encoded data slices.

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

send, via the interface, an unavailable message to the requester when the set of encoded data slices is unable to be retrieved after a number of time varying availability patterns.

16. The computing device of claim 9 , wherein the requester is at least one of: a user device, a dispersed storage (DS) processing unit, a storage integrity processing unit, and a managing unit.