Recovering Data in a Storage Network via Locally Decodable Redundancy Data
A storage network is operable to obtain a first subset of a set of encoded data slices, where the set of encoded data slices correspond to data that is coded in accordance with dispersed error coding parameters that include a read threshold number, and where the read threshold number is a number of the set of encoded data slices that is required to decode the data. Based on the number of encoded data slices in the first subset being less than the read threshold number, at least one rebuilt encoded data slice corresponding to at least one additional encoded data slice of the set of data slices not included in the first subset of the set of encoded data slices is generated utilizing locally decodable redundancy data. The data is recovered based on the at least one rebuilt encoded data slice and the first subset.
1 . A method for execution by at least one processing circuit of a storage network, the method comprises:
obtaining, via the at least one processing circuit, a first subset of a set of encoded data slices, wherein the set of encoded data slices correspond to data that is coded in accordance with dispersed error coding parameters that include a read threshold number, wherein the read threshold number is a number of the set of encoded data slices that is required to decode the data;
based on the number of encoded data slices in the first subset being less than the read threshold number, generating, via the at least one processing circuit, at least one rebuilt encoded data slice corresponding to at least one additional encoded data slice of the set of data slices not included in the first subset of the set of encoded data slices utilizing locally decodable redundancy data, wherein the locally decodable redundancy data corresponds to a second subset of the set of encoded data slices that includes the at least one additional encoded data slice; and
recovering, via the at least one processing circuit, the data based on the at least one rebuilt encoded data slice and the first subset.
2 . The method of claim 1 , wherein at least one missing encoded data slice was not included in the first subset and wherein a number of encoded data slices in the first subset is less than the read threshold number, further comprising:
identifying, via the at least one processing circuit, the at least one missing encoded data slice of the first subset.
3 . The method of claim 2 , wherein the at least one missing encoded data slice of the first subset is identified when the at least one missing encoded data slice was not received from the at least one storage unit in response to the at least one read request.
4 . The method of claim 1 , wherein the second subset of the set of encoded data slices includes less than the read threshold number of the set of encoded data slices.
5 . The method of claim 1 , wherein at least one missing encoded data slice was not included in the first subset and wherein a number of encoded data slices in the first subset is less than the read threshold number, wherein the at least one missing encoded data slice corresponds to failure of an individual storage device of the at least one storage unit.
6 . The method of claim 5 , wherein the individual storage device is a drive that failed.
7 . The method of claim 1 , further comprising:
selecting the second subset of the set of encoded data slices to generate the locally decodable redundancy data.
8 . A storage network system of a storage network comprises:
at least one processing circuit;
a memory that stores operational instructions, that when executed by the at least one processing circuit cause the storage processing system to perform operations that include:
obtaining, via the at least one processing circuit, a first subset of a set of encoded data slices, wherein the set of encoded data slices correspond to data that is coded in accordance with dispersed error coding parameters that include a read threshold number, wherein the read threshold number is a number of the set of encoded data slices that is required to decode the data;
based on the number of encoded data slices in the first subset being less than the read threshold number, generating, via the at least one processing circuit, at least one rebuilt encoded data slice corresponding to at least one additional encoded data slice of the set of data slices not included in the first subset of the set of encoded data slices utilizing locally decodable redundancy data, wherein the locally decodable redundancy data corresponds to a second subset of the set of encoded data slices that includes the at least one additional encoded data slice; and
recovering, via the at least one processing circuit, the data based on the at least one rebuilt encoded data slice and the first subset.
9 . The storage network system of claim 8 , wherein at least one missing encoded data slice was not included in the first subset and wherein a number of encoded data slices in the first subset is less than the read threshold number, wherein the operations further include:
identifying, via the at least one processing circuit, the at least one missing encoded data slice of the first subset.
10 . The storage network system of claim 9 , wherein the at least one missing encoded data slice of the first subset is identified when the at least one missing encoded data slice was not received from the at least one storage unit in response to the at least one read request.
11 . The storage network system of claim 8 , wherein the second subset of the set of encoded data slices includes less than the read threshold number of the set of encoded data slices.
12 . The storage network system of claim 8 , wherein at least one missing encoded data slice was not included in the first subset and wherein a number of encoded data slices in the first subset is less than the read threshold number, wherein the at least one missing encoded data slice corresponds to failure of an individual storage device of the at least one storage unit.
13 . The storage network system of claim 12 , wherein the individual storage device is a drive that failed.
14 . The storage network system of claim 8 , wherein the operations further include:
selecting the second subset of the set of encoded data slices to generate the locally decodable redundancy data.
15 . A non-transitory computer readable storage medium comprises:
at least one memory that stores operational instructions that, when executed by a storage network that includes at least one processing circuit and a memory, causes the storage network to perform operations that include:
obtaining, via the at least one processing circuit, a first subset of a set of encoded data slices, wherein the set of encoded data slices correspond to data that is coded in accordance with dispersed error coding parameters that include a read threshold number, wherein the read threshold number is a number of the set of encoded data slices that is required to decode the data;
based on the number of encoded data slices in the first subset being less than the read threshold number, generating, via the at least one processing circuit, at least one rebuilt encoded data slice corresponding to at least one additional encoded data slice of the set of data slices not included in the first subset of the set of encoded data slices utilizing locally decodable redundancy data, wherein the locally decodable redundancy data corresponds to a second subset of the set of encoded data slices that includes the at least one additional encoded data slice; and
recovering, via the at least one processing circuit, the data based on the at least one rebuilt encoded data slice and the first subset.
16 . The non-transitory computer readable storage medium of claim 15 , wherein at least one missing encoded data slice was not included in the first subset and wherein a number of encoded data slices in the first subset is less than the read threshold number, wherein the operations further include:
identifying, via the at least one processing circuit, the at least one missing encoded data slice of the first subset.
17 . The non-transitory computer readable storage medium of claim 16 , wherein the at least one missing encoded data slice of the first subset is identified when the at least one missing encoded data slice was not received from the at least one storage unit in response to the at least one read request.
18 . The non-transitory computer readable storage medium of claim 16 , wherein the second subset of the set of encoded data slices includes less than the read threshold number of the set of encoded data slices.
19 . The non-transitory computer readable storage medium of claim 15 , wherein at least one missing encoded data slice was not included in the first subset and wherein a number of encoded data slices in the first subset is less than the read threshold number, wherein the at least one missing encoded data slice corresponds to failure of an individual storage drive of the at least one storage unit.
20 . The non-transitory computer readable storage medium of claim 15 , wherein the operations further include:
selecting the second subset of the set of encoded data slices to generate the locally decodable redundancy data.