INDICATING MULTIPLE ENCODING SCHEMES IN A DISPERSED STORAGE NETWORK

• US 20170353553A1
• Filed: 06/06/2016
• Published: 12/07/2017
• Est. Priority Date: 06/06/2016
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wozniak, Ethan S.
• Granted Patent: US 10,334,045 B2
• Time in Patent Office: Days
• CPC Class Codes: H04L 49/901 using storage descriptor, e.g. read or write pointers
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

A method includes transmitting a first write request that includes a first encoded data slice of a first data object encoded under a first encoding scheme, and a first slice identifier corresponding to the first encoded data slice assigned to a first memory location of a distributed storage network (DSN) based on the first slice identifier. A second write request that includes a second encoded data slice of the first data object encoded under a second encoding scheme, and a second slice identifier corresponding to the second encoded data slice, is transmitted, and the second encoded data slice is assigned to a second memory location of the DSN based on the second slice identifier. A request to access the first data object is received. A derived second slice identifier is generated in response to determining that the first data object requested for access is stored under multiple encoding schemes.

Claims

1. A method for execution by a dispersed storage and task (DST) processing unit that includes a processor, the method comprises:

transmitting via a network a first write request that includes at least one first encoded data slice of a first data object, and a first slice identifier corresponding to the at least one first encoded data slice, wherein the at least one first encoded data slice is encoded under a first encoding scheme, and wherein the at least one first encoded data slice is assigned to at least one first memory location of a distributed storage network (DSN) based on the first slice identifier;

transmitting via the network a second write request that includes at least one second encoded data slice of the first data object, and a second slice identifier corresponding to the at least one second encoded data slice, wherein the at least one second encoded data slice is encoded under a second encoding scheme, and wherein the at least one second encoded data slice is assigned to at least one second memory location of the DSN based on the second slice identifier;

receiving via the network a first access request to access the first data object;

generating a derived second slice identifier in response to determining that the first data object requested for access is stored under multiple encoding schemes; and

transmitting via the network a first read request that includes the derived second slice identifier to access the at least one second encoded data slice.

2. The method of claim 1, further comprising:

generating the second slice identifier by performing a deterministic function on the first slice identifier; and

generating a derived first slice identifier based on the first access request;

wherein the derived second slice identifier is generated by performing the deterministic function on the derived first slice identifier.

3. The method of claim 2, wherein the deterministic function is one of:

a hash function or a mask generating function.

4. The method of claim 1, further comprising:

generating a new first object identifier to indicate the first data object; and

replacing an original first object identifier that identifies the first data object with the new first object identifier.

5. The method of claim 4, further comprising transmitting the new first object identifier to a requesting entity in response to generating the new first object identifier, wherein the first access request is received from the requesting entity, and wherein the first access request includes the new first object identifier.

6. The method of claim 5, wherein generating the new first object identifier includes updating a reserved field of the original first object identifier, further comprising performing a test on the reserved field in response to receiving the new first object identifier in the first access request, and wherein the derived second slice identifier is generated in response to a result of the test indicating that the first data object is stored under multiple encoding schemes.

7. The method of claim 4, wherein the new object first identifier is generated by utilizing a reversible function on the original first object identifier, further comprising:

generating the first slice identifier based on the original first object identifier;

generating a derived original first object identifier by utilizing an inverse function of the reversible function on the new first object identifier; and

generating a derived first slice identifier based on the derived original first object identifier;

wherein the derived second slice identifier is generated by performing a deterministic function on the first slice identifier.

8. The method of claim 7, wherein the reversible function includes multiplying the original first object identifier by a large prime number to generate the new first object identifier, and wherein determining that the first data object is stored under multiple encoding schemes includes determining that a quotient of a division of the new first object identifier by the large prime number is an integer, and wherein the derived original first object identifier is based on the quotient.

9. The method of claim 1, further comprising:

receiving a second access request via the network to access a second data object, wherein the second data object is stored as at least one third encoded data slice, and wherein no encoded data slices are stored under additional encoding schemes that correspond to the second data object;

generating a derived third slice identifier in response to determining that the second data object requested for access is not stored under multiple encoding schemes; and

transmitting via the network a second read request that includes the derived third slice identifier to access the at least one third encoded data slice.

10. The method of claim 9, further comprising dividing an original second object identifier by a large prime number, wherein the derived third slice identifier is generated in response to determining that a quotient of the division is not an integer.

11. The method of claim 1, wherein the first encoding scheme corresponds to performing an information dispersal algorithm by utilizing a first set of parameters, and wherein the second encoding scheme corresponds to performing the information dispersal algorithm by utilizing a second set of parameters.

12. The method of claim 4, wherein the new first object identifier indicates that the at least one second encoded data slice is preferred over the at least one first encoded data slice when performing access requests.

13. A processing system of a dispersed storage and task (DST) processing unit comprises:

at least one processor;

a memory that stores operational instructions, that when executed by the at least one processor cause the processing system to;

transmit via a network a first write request that includes at least one first encoded data slice of a first data object, and a first slice identifier corresponding to the at least one first encoded data slice, wherein the at least one first encoded data slice is encoded under a first encoding scheme, and wherein the at least one first encoded data slice is assigned to at least one first memory location of a distributed storage network (DSN) based on the first slice identifier;

transmit via the network a second write request that includes at least one second encoded data slice of the first data object, and a second slice identifier corresponding to the at least one second encoded data slice, wherein the at least one second encoded data slice is encoded under a second encoding scheme, and wherein the at least one second encoded data slice is assigned to at least one second memory location of the DSN based on the second slice identifier;

receive via the network an first access request to access the first data object;

generate a derived second slice identifier in response to determining that the first data object requested for access is stored under multiple encoding schemes; and

transmit via the network a first read request that includes the derived second slice identifier to access the at least one second encoded data slice.

14. The processing system of claim 13, wherein the operational instructions, when executed by the at least one processor, further cause the processing system to:

generate the second slice identifier by performing a deterministic function on the first slice identifier; and

generate a derived first slice identifier based on the first access request;

wherein the derived second slice identifier is generated by performing the deterministic function on the derived first slice identifier.

15. The processing system of claim 13, wherein the operational instructions, when executed by the at least one processor, further cause the processing system to:

generate a new first object identifier to indicate the first data object; and

replace an original first object identifier that identifies the first data object with the new first object identifier.

16. The processing system of claim 15, wherein the new object first identifier is generated by utilizing a reversible function on the original first object identifier, and wherein the operational instructions, when executed by the at least one processor, further cause the processing system to:

generate the first slice identifier based on the original first object identifier;

generate a derived original first object identifier by utilizing an inverse function of the reversible function on the new first object identifier; and

generate a derived first slice identifier based on the derived original first object identifier;

wherein the derived second slice identifier is generated by performing a deterministic function on the first slice identifier.

17. The processing system of claim 16, wherein the reversible function includes multiplying the original first object identifier by a large prime number to generate the new first object identifier, and wherein determining that the first data object is stored under multiple encoding schemes includes determining that a quotient of a division of the new first object identifier by the large prime number is an integer, and wherein the derived original first object identifier is based on the quotient.

18. The processing system of claim 13, wherein the operational instructions, when executed by the at least one processor, further cause the processing system to:

receiving a second access request via the network to access a second data object, wherein the second data object is stored as at least one third encoded data slice, and wherein no encoded data slices are stored under additional encoding schemes that correspond to the second data object;

generating a derived third slice identifier in response to determining that the second data object requested for access is not stored under multiple encoding schemes; and

transmitting via the network a second read request that includes the derived third slice identifier to access the at least one third encoded data slice.

19. The processing system of claim 15, wherein the new first object identifier indicates that the at least one second encoded data slice is preferred over the at least one first encoded data slice when performing access requests.

20. 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 a processor and a memory, causes the processing system to;

transmit via a network a first write request that includes at least one first encoded data slice of a first data object, and a first slice identifier corresponding to the at least one first encoded data slice, wherein the at least one first encoded data slice is encoded under a first encoding scheme, and wherein the at least one first encoded data slice is assigned to at least one first memory location of the DSN based on the first slice identifier;

transmit via the network a second write request that includes at least one second encoded data slice of the first data object, and a second slice identifier corresponding to the at least one second encoded data slice, wherein the at least one second encoded data slice is encoded under a second encoding scheme, and wherein the at least one second encoded data slice is assigned to at least one second memory location of the DSN based on the second slice identifier;

receive via the network a first access request to access the first data object;

generate a derived second slice identifier in response to determining that the first data object requested for access is stored under multiple encoding schemes; and

transmit via the network a first read request that includes the derived second slice identifier to access the at least one second encoded data slice.