# US 11,113,146 B2 · Chunk segment recovery via hierarchical erasure coding in a geographically diverse data storage system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,113,146 B2 - Document ID: US11113146B2 - Status: Granted - Kind: B2 - Application number: 16/399,895 - Filed: 2019-04-30 - Published: 2020-11-05 - Granted: 2021-09-07 - Earliest claimed: 2019-04-30 - Assignees: EMC IP Holding Company LLC - Applicants: EMC IP Holding Company LLC - Inventors: Mikhail Danilov; Yohannes Altaye - Web page: https://patentgrep.com/patent/US11113146B2 ## CPC - G06F 11/1076: {Parity data used in redundant arrays of independent storages, e.g. in RAID systems} - G06F 3/0619: {in relation to data integrity, e.g. data losses, bit errors} - G06F 3/064: {Management of blocks} - G06F 3/0659: {Command handling arrangements, e.g. command buffers, queues, command scheduling} - G06F 3/067: {Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]} - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract Recovery of chunk segments stored via hierarchical erasure coding in a geographically diverse data storage system is disclosed. Chunks can be stored according to a first-level erasure coding scheme in zones of a geographically diverse data storage system. The chunks can then be further protected via one or more second-level erasure coding schema within a corresponding zone of the geographically diverse data storage system. In response to determining segment of a chunk has become less accessible, recover of the segment can be performed according to the hierarchical erasure coding scheme of relevant chunks at relevant zones of the geographically diverse data storage system. ## Claims ### Claim 1 A system, comprising: a processor; and a memory that stores executable instructions that, when executed by the processor, facilitate performance of operations, comprising: in response to determining that a first segment has become inaccessible, determining an index of the first segment, wherein the first segment is comprised in a first chunk of a first zone of zones of a geographically diverse data storage system, and wherein the zones of the geographically diverse data storage system employ hierarchical erasure coding; determining a second chunk of a second zone of the zones based on the hierarchical erasure coding, wherein the second chunk and the second zone are determined to be relevant to a recovery of the first segment; determining a second segment of the second relevant chunk based on the index and the hierarchical erasure coding, wherein the second segment is determined to be relevant to the recovery of the first segment; generating a first recovered segment based in at least in part on the second segment and the hierarchical erasure coding, wherein the first recovered segment represents the same information as was represented on the first segment prior to the first segment becoming inaccessible. ### Claim 2 (depends on 1) The system of claim 1, wherein the operations further comprise replacing the first segment with the first recovered segment in the first chunk of the first zone of the geographically diverse data storage system. ### Claim 3 (depends on 2) The system of claim 2, wherein the first segment is stored in part in a first physical memory cell of a first storage device of the first zone, wherein the replacing the first segment with the first recovered segment occurs at a second physical memory cell of a second storage device of the first zone, and wherein the first physical memory cell is a different physical memory cell than the second physical memory cell. ### Claim 4 (depends on 3) The system of claim 3, wherein the first storage device is a different storage device than the second storage device. ### Claim 5 (depends on 1) The system of claim 1, wherein the hierarchical erasure coding comprises a first-level erasure coding scheme and at least a first second-level erasure coding scheme. ### Claim 6 (depends on 5) The system of claim 5, wherein the first-level erasure coding scheme is a zone-level erasure coding scheme that protects at a whole chunk level across the zones of the geographically diverse data storage system. ### Claim 7 (depends on 6) The system of claim 6, wherein the zone-level erasure coding scheme is a ‘4+2’ erasure coding scheme. ### Claim 8 (depends on 5) The system of claim 5, wherein the first second-level erasure coding scheme is a first chunk-level erasure coding scheme that protects at a chunk-segment level across the first chunk of the first zone of the geographically diverse data storage system. ### Claim 9 (depends on 8) The system of claim 8, wherein a second second-level erasure coding scheme is a second chunk-level erasure coding scheme that protects at a chunk-segment level across a second chunk of the first zone of the geographically diverse data storage system. ### Claim 10 (depends on 9) The system of claim 9, wherein the first chunk-level erasure coding scheme is a different chunk-level erasure coding scheme than the second chunk-level erasure coding scheme. ### Claim 11 (depends on 10) The system of claim 10, wherein the first chunk-level erasure coding scheme is a ‘12+4’ chunk-level erasure coding scheme. ### Claim 12 (depends on 10) The system of claim 10, wherein the first chunk-level erasure coding scheme is a ‘10+2’ chunk-level erasure coding scheme. ### Claim 13 (depends on 9) The system of claim 9, wherein the first chunk-level erasure coding scheme is a same chunk-level erasure coding scheme as the second chunk-level erasure coding scheme. ### Claim 14 (depends on 13) The system of claim 13, wherein the first chunk-level erasure coding scheme is selected from a group of chunk-level erasure coding schema comprising a ‘12+4’ chunk-level erasure coding scheme and a ‘10+2’ chunk-level erasure coding scheme. ### Claim 15 A method, comprising: determining, by a system comprising a processor and a memory, an index of a first segment, wherein the first segment is comprised in a first chunk of a first zone of zones of a geographically diverse data storage system, and wherein the zones of the geographically diverse data storage system store data according to a hierarchical erasure coding scheme; determining, by the system, a second chunk of a second relevant zone of the zones based on the hierarchical erasure coding scheme, wherein the second chunk is determined to be a relevant chunk based on the hierarchical erasure coding scheme, and wherein the second zone is determined to be a relevant zone based on the hierarchical erasure coding scheme; determining, by the system, a second segment of the second relevant chunk, wherein the second segment is determined to be a relevant segment based on the index and the hierarchical erasure coding scheme; in response to receiving an indication that the first segment is inaccessible, replacing, by the system, the first segment with a first recovered segment that is determined based, at least in part, on the second segment and on the hierarchical erasure coding scheme, wherein the first recovered segment represents information that was represented on the first segment prior to the first segment becoming inaccessible. ### Claim 16 (depends on 15) The method of claim 15, wherein the hierarchical erasure coding comprises a zone-level erasure coding scheme and at least a first chunk-level erasure coding scheme. ### Claim 17 (depends on 16) The method of claim 16, wherein the zone-level erasure coding scheme is a ‘4+2’ erasure coding scheme, and wherein the first chunk-level erasure coding scheme is selected from a group of chunk-level erasure coding schema comprising a ‘12+4’ chunk-level erasure coding scheme and a ‘10+2’ chunk-level erasure coding scheme. ### Claim 18 A device, comprising: a processor; and a memory that stores executable instructions that, when executed by the processor, facilitate performance of operations, comprising: in response to receiving an indication that a first segment is inaccessible, determining an index of the first segment, wherein the first segment is comprised in a first chunk of a first zone of zones of a geographically diverse data storage system, and wherein the zones of the geographically diverse data storage system store data according to a hierarchical erasure coding scheme; determining a second segment of a second chunk of a second zone of the zones based on the index and on the hierarchical erasure coding scheme, wherein the second segment, the second chunk, and the second zone are used in connection with a recovery of the first segment; replacing, by the system, the first segment with a first recovered segment that is determined based, at least in part, on the second segment and on the hierarchical erasure coding scheme, wherein the first recovered segment represents information that was represented on the first segment prior to the first segment becoming inaccessible. ### Claim 19 (depends on 18) The device of claim 18, wherein the hierarchical erasure coding comprises a first-level erasure coding scheme and at least a first second-level erasure coding scheme. ### Claim 20 (depends on 19) The device of claim 19, wherein the first-level erasure coding scheme is a ‘4+2’ erasure coding scheme, and wherein the first second-level erasure coding scheme is selected from a group of second-level erasure coding schema comprising at least a ‘12+4’ chunk-level erasure coding scheme and a ‘10+2’ chunk-level erasure coding scheme.