Managing Correlated Outages in a Dispersed Storage Network

Abstract

A storage network processing system includes a processor, a network interface and memory that stores operational instructions. The operation instructions enable the processor to receive a data object for storage and dispersed error encode the data object in accordance with dispersed error encoding parameters to produce a plurality of encoded data slices. The operation instructions further enable the processor to generate to determine a plurality of site slice sets from the plurality of encoded data slices, where each site slice set of the plurality of site slice sets includes a number of unique encoded data slices of the plurality of encoded data slices that is greater than or equal to a site write threshold value. The operation instructions further enable the processor to a designate one of a plurality of storage sites for each of the plurality of site slice sets and transmit each of the plurality of site slice sets to a corresponding designated one of the plurality of storage sites via the network.

What is claimed is: 
     
         1 . A method comprises:
 receiving, by a storage network processing module, a data object for storage via the network;   dispersed error encoding, by the storage network processing module, the data object in accordance with dispersed error encoding parameters to produce a plurality of encoded data slices;   generating, by the storage network processing module, information sufficient to determine a plurality of site slice sets, wherein each site slice set of the plurality of site slice sets includes a number of unique encoded data slices of the plurality of encoded data slices that is greater than or equal to a site write threshold value, wherein the information indicates a designated one of a plurality of storage sites for each of the plurality of site slice sets; and   transmitting, by the storage network processing module, each of the plurality of site slice sets to a corresponding designated one of the plurality of storage sites via the network.   
     
     
         2 . The method of  claim 1 , wherein the site write threshold value is based on an information dispersal algorithm (IDA) encoding function. 
     
     
         3 . The method of  claim 2 , further comprising:
 generating dispersal parameter data indicating the site write threshold value based on an information dispersal algorithm (IDA) threshold value and a maximum number of sites value.   
     
     
         4 . The method of  claim 3 , wherein generating the dispersal parameter data includes dividing the IDA threshold value by the maximum number of sites value to determine the site write threshold value. 
     
     
         5 . The method of  claim 3 , further comprising calculating the maximum number of sites value based on at least one of a site availability level or a site reliability level. 
     
     
         6 . The method of  claim 3 , wherein each of the plurality of storage sites includes a plurality of storage units, wherein the dispersal parameter data further indicates a designated storage unit for each encoded slice in each of the plurality of site slice sets. 
     
     
         7 . The method of  claim 1 , wherein each site slice set is a proper subset of the plurality of encoded slices, and wherein the number of unique encoded data slices of each site slice set is equal to the site write threshold value. 
     
     
         8 . The method of  claim 1 , wherein each of the plurality of storage sites are located in different physical locations. 
     
     
         9 . A storage network processing system comprises:
 at least one processing unit;   a network interface;   a memory that stores operational instructions, that when executed by the at least one processor cause the processing system to:
 receive a data object for storage; 
 dispersed error encode the data object in accordance with dispersed error encoding parameters to produce a plurality of encoded data slices; 
 generate information sufficient to determine a plurality of site slice sets, wherein each site slice set of the plurality of site slice sets includes a number of unique encoded data slices of the plurality of encoded data slices that is greater than or equal to a site write threshold value, wherein the information indicates a designated one of a plurality of storage sites for each of the plurality of site slice sets; and 
 transmit each of the plurality of site slice sets to a corresponding designated one of the plurality of storage sites via the network. 
   
     
     
         10 . The processing system of  claim 9 , wherein the site write threshold value is based on an information dispersal algorithm (IDA) encoding function. 
     
     
         11 . The processing system of  claim 10 , wherein the operational instructions, when executed by the at least one processor, further cause the processing unit to generate dispersal parameter data indicating the site write threshold value based on an information dispersal algorithm (IDA) threshold value and a maximum number of sites value. 
     
     
         12 . The processing system of  claim 11 , wherein the operational instructions, when executed by the at least one processor, further cause the processing unit to generate dispersal parameter data by dividing the IDA threshold value by the maximum number of sites value to determine the site write threshold value. 
     
     
         13 . The processing system of  claim 11 , wherein the operational instructions, when executed by the at least one processor, further cause the processing unit to calculate the maximum number of sites value based on at least one of a site availability level or a site reliability level. 
     
     
         14 . The processing system of  claim 11 , wherein each of the plurality of storage sites includes a plurality of storage units, wherein the dispersal parameter data further indicates a designated storage unit for each encoded slice in each of the plurality of site slice sets. 
     
     
         15 . The processing system of  claim 9 , wherein each of the plurality of site slice sets is a proper subset of the plurality of encoded slices, and wherein the number of unique encoded slices of each site slice set is equal to the site write threshold value. 
     
     
         16 . The processing system of  claim 9 , wherein each of the plurality of storage sites are located in different physical locations. 
     
     
         17 . A non-transitory computer readable storage medium comprises:
 at least one memory section that stores operational instructions that, when executed by a processing system of a dispersed storage network (DSN) that includes at least one processor and a memory, causes the processing system to:
 receive a data object for storage; 
 dispersed error encode the data object in accordance with dispersed error encoding parameters to produce a plurality of encoded data slices; 
 generate information sufficient to determine a plurality of site slice sets, wherein each site slice set of the plurality of site slice sets includes a number of unique encoded data slices of the plurality of encoded data slices that is greater than or equal to a site write threshold value, wherein the information indicates a designated one of a plurality of storage sites for each of the plurality of site slice sets; and 
 transmit each of the plurality of site slice sets to a corresponding designated one of the plurality of storage sites via the network. 
   
     
     
         18 . The non-transitory computer readable storage medium of  claim 17  wherein the operational instructions, when executed by the processing system, further cause the non-transitory computer readable storage medium to generate dispersal parameter data indicating the site write threshold value by executing an information dispersal algorithm (IDA) encoding function. 
     
     
         19 . The non-transitory computer readable storage medium of  claim 18 , wherein the operational instructions, when executed by the at least one processor, further cause at least one processor to generate dispersal parameter data indicating the site write threshold value based on an information dispersal algorithm (IDA) threshold value and a maximum number of sites value. 
     
     
         20 . The non-transitory computer readable storage medium of  claim 17 , wherein each of the plurality of storage sites are located in different physical locations.