METHOD AND APPARATUS FOR NESTED DISPERSED STORAGE

• US 20150149861A1
• Filed: 02/02/2015
• Published: 05/28/2015
• Est. Priority Date: 08/27/2009
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Cleversafe Incorporated (International Business Machines Corporation)
• Inventors: Grube, Gary W., Markison, Timothy W.
• Granted Patent: US 9,189,336 B2
• Time in Patent Office: Days
• US Class Current: 714/763
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 11/1088 Reconstruction on already foreseen single or plurality of spare disks
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G06F 21/6272 by registering files or documents with a third party
• CPC Class Codes: H04L 63/126 the source of the received data

Abstract

A method begins by a DS processing module generating a plurality of encoded slices from a data segment using an error encoding function. The method continues with the DS processing module identifying a plurality of DS storage units for storing the plurality of encoded slices. The method continues with the DS processing module selecting an encoded slice of the plurality of encoded slices for sub-slicing using a sub-slicing encoding function to produce a selected encoded slice. The method continues with the DS processing module outputting the plurality of encoded slices to the plurality of DS storage units. The method continues with the DS processing module outputting a command to a DS storage unit of the plurality of DS storage units corresponding to the selected encoded slice, wherein the command includes an instruction to sub-slice the selected encoded slice.

Claims

1. A method for retrieving data from a dispersed storage network comprising:

processing a request to reconstruct a data segment at a processing module, in which the data segment is dispersed error encoded to produce a plurality of data slices and in which at least one data slice of the plurality of data slices is further dispersed error encoded to produce a respective plurality of data sub-slices, wherein the data slices and the data sub-slices are stored in a plurality of dispersed storage units;

identifying locations of the data slices and data sub-slices stored in the plurality of dispersed storage units; and

retrieving a first threshold number of the data slices to reconstruct the data segment and when retrieving a particular data slice, the particular data slice is further sub-sliced, the particular data slice is reconstructed by retrieving a second threshold number of respective data sub-slices corresponding to the particular data slice to reconstruct the particular data slice.

2. The method of claim 1, wherein when identifying the locations, the processing module identifies the locations of the data slices and data sub-slices stored in the dispersed storage units.

3. The method of claim 2, wherein the processing module sends instructions to retrieve the data slices and the data sub-slices to the plurality of dispersed storage units.

4. The method of claim 1, wherein when identifying the locations, the processing module identifies the locations of the data slices stored in the plurality of dispersed storage units and for the at least one data slice having the respective plurality of data sub-slices, a corresponding dispersed storage unit or units storing the at least one data slice identifies the locations of the respective data sub-slices.

5. The method of claim 4, wherein the processing module sends instructions to retrieve the data slices and corresponding dispersed storage units having the data slices that are further sub-sliced send instructions to retrieve the data sub-slices.

6. The method of claim 1, wherein when identifying the locations, the locations are stored in a memory accessible by the dispersed storage network.

7. The method of claim 1, wherein one or more data sub-slices are further sub-sliced into a respective plurality of data sub-sub-slices and, when retrieving a particular data sub-slice, a third threshold number of respective data sub-sub-slices corresponding to the particular data sub-slice is retrieved to reconstruct the particular data sub-slice.

8. The method of claim 1, further comprising reconstructing the data segment from the retrieved data slices and data sub-slices.

9. An apparatus for retrieving data from a dispersed storage network comprising:

an interface configured to operate with the dispersed storage network; and

a processing module to reconstruct a data segment, in which the data segment is dispersed error encoded to produce a plurality of data slices and in which at least one data slice of the plurality of data slices is further dispersed error encoded to produce a respective plurality of data sub-slices, wherein the data slices and the data sub-slices are stored in a plurality of dispersed storage units, the processing module to identify locations of the data slices stored in the plurality of dispersed storage units, and the processing module to retrieve a first threshold number of the data slices to reconstruct the data segment and when retrieving a particular data slice, the particular data slice is further sub-sliced, the particular data slice is reconstructed by retrieving a second threshold number of respective data sub-slices corresponding to the particular data slice to reconstruct the particular data slice.

10. The apparatus of claim 9, wherein the processing module also identifies the locations of the data sub-slices stored in the dispersed storage units for the at least one data slice having sub-slices.

11. The apparatus of claim 10, wherein the processing module sends instructions to retrieve the data slices and the data sub-slices to the plurality of dispersed storage units.

12. The apparatus of claim 9, wherein when the processing module attempts to retrieve the data slices stored in the plurality of dispersed storage units, for the at least one data slice having respective plurality of data sub-slices, causes a corresponding dispersed storage unit or units storing the at least one data slice to identify the locations of the respective data sub-slices.

13. The apparatus of claim 12, wherein the processing module sends instructions to retrieve the data slices and corresponding dispersed storage units having the data slices that are further sub-sliced send instructions to retrieve the data sub-slices.

14. The apparatus of claim 9, further comprising a memory configured to operate with the processing module to store the locations.

15. The apparatus of claim 9, wherein the processing module reconstructs the data segment from the retrieved data slices and data sub-slices.

16. A non-transitory computer readable medium having stored thereon instructions which, when executed, performs operations to retrieve data from a dispersed storage network comprising:

processing a request to reconstruct a data segment at a processing module, in which the data segment is dispersed error encoded to produce a plurality of data slices and in which at least one data slice of the plurality of data slices is further dispersed error encoded to produce a respective plurality of data sub-slices, wherein the data slices and the data sub-slices are stored in a plurality of dispersed storage units;

identifying locations of the data slices stored in the plurality of dispersed storage units; and

retrieving a first threshold number of the data slices to reconstruct the data segment and when retrieving a particular data slice, the particular data slice is further sub-sliced, the particular data slice is reconstructed by retrieving a second threshold number of respective data sub-slices corresponding to the particular data slice to reconstruct the particular data slice.

17. The non-transitory computer readable medium of claim 16, wherein the instructions, when executed, cause the processing module to also identify the locations of the data sub-slices stored in the dispersed storage units.

18. The non-transitory computer readable medium of claim 16, wherein the instructions, when executed, cause the processing module to attempt to retrieve the data slices stored in the plurality of dispersed storage units, for the at least one data slice having respective plurality of data sub-slices, causes a corresponding dispersed storage unit or units storing the at least one data slice to identify the locations of the respective data sub-slices.

19. The non-transitory computer readable medium of claim 18, wherein the instructions, when executed, cause the processing module to send instructions to retrieve the data slices and causes corresponding dispersed storage unit or units having the data slices that are further sub-sliced to send instructions to retrieve the data sub-slices.

20. The non-transitory computer readable medium of claim 16, wherein the instructions, when executed, cause the processing module to reconstruct the data segment from the retrieved data slices and data sub-slices.