Intentionally introduced storage deviations in a dispersed storage network

• US 8,522,074 B2
• Filed: 07/23/2010
• Issued: 08/27/2013
• Est. Priority Date: 10/29/2009
• Status: Expired due to Fees

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Cleversafe Incorporated (International Business Machines Corporation)
• Inventors: Markison, Timothy W., Grube, Gary W., Gladwin, S. Christopher, Holmes, Alan E., Leggette, Wesley, Resch, Jason K.
• Primary Examiner(s): Baderman, Scott
• Assistant Examiner(s): BRYAN, JASON B
• Application Number:
  US12/842,932
• Publication Number:
  US 20110107180A1
• Time in Patent Office: 1,131 Days
• Field of Search: None
• US Class Current: 714/6.24
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G11C 29/52 Protection of memory contents; Detection of errors in memory contents
• CPC Class Codes: H03M 13/09 Error detection only, e.g. using cyclic redundancy check [CRC] codes or single parity bit
• CPC Class Codes: H03M 13/15 Cyclic codes, i.e. cyclic shifts of codewords produce other codewords, e.g. codes defined by a generator polynomial, Bose-Chaudhuri-Hocquenghem [BCH] codes H03M13/17 takes precedence
• CPC Class Codes: H03M 13/1515 Reed-Solomon codes
• CPC Class Codes: H03M 13/23 using convolutional codes, e.g. unit memory codes
• CPC Class Codes: H03M 13/356 Unequal error protection [UEP]
• CPC Class Codes: H04N 21/2181 comprising remotely distributed storage units, e.g. when movies are replicated over a plurality of video servers distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: H04N 21/23439 for generating different versions
• CPC Class Codes: H04N 21/2393 involving handling client requests scheduling or organising the servicing of application requests H04L67/60
• CPC Class Codes: H04N 21/274 Storing end-user multimedia data in response to end-user request , e.g. network recorder
• CPC Class Codes: H04N 21/2747 Remote storage of video programs received via the downstream path, e.g. from the server
• CPC Class Codes: H04N 21/6587 Control parameters, e.g. trick play commands, viewpoint selection

Abstract

A method begins by a processing module receiving a first request to store a program. The method continues with the processing module determining first error coding dispersal storage function parameters and encoding a data segment of the program. The method continues with the processing module determining whether a second request to store the program is received. The method continues with the processing module encoding a second data segment of the program in accordance with the first error coding dispersal storage function parameters when the second request is not received. The method continues with the processing module changing the first error coding dispersal storage function parameters based on the another request to produce second error coding dispersal storage function parameters when the second request is received. The method continues with the processing module encoding the second data segment in accordance with the second error coding dispersal storage function parameters.

Claims

1. A method for execution by a dispersed storage (DS) processing module, the method comprises:

receiving a first request to store a program;

determining first error coding dispersal storage function parameters;

encoding a data segment of the program in accordance with the first error coding dispersal storage function parameters;

determining whether a second request to store the program is received;

when the second request is not received, encoding a second data segment of the program in accordance with the first error coding dispersal storage function parameters;

when the second request is received, changing the first error coding dispersal storage function parameters based on the second request to produce second error coding dispersal storage function parameters; and

encoding the second data segment in accordance with the second error coding dispersal storage function parameters.

2. The method of claim 1 further comprises:

determining whether another request to store the program is received, wherein the another request is received, in time, between the first and second requests;

when the other request is received, determining whether to change the first error coding dispersal storage function parameters;

when the first error coding dispersal storage function parameters are to be changed, changing the first error coding dispersal storage function parameters based on the other request to produce third error coding dispersal storage function parameters; and

encoding another data segment in accordance with the third error coding dispersal storage function parameters.

3. The method of claim 1, wherein the changing the first error coding dispersal storage function parameters based on the second request comprises:

changing a post-slice data manipulation function that includes at least one of;

an error injection function;

a bit dithering function;

a bit rotation function;

a slice comparison function;

a watermark function;

a hash function; and

a bit swapping function.

4. The method of claim 1 further comprises at least one of:

determining a first playback error coding dispersal storage function parameter set for a requesting device associated with the first request based on the first error coding dispersal storage function parameters and subsequent changes to the first error coding dispersal storage function parameters;

determining a second playback error coding dispersal storage function parameter set for a second requesting device associated with the second request based on the second error coding dispersal storage function parameters and subsequent changes to the second error coding dispersal storage function parameters;

outputting the first playback error coding dispersal storage function parameter set to the first requesting device; and

outputting the second playback error coding dispersal storage function parameter set to the second requesting device.

5. The method of claim 1, wherein the first and second error coding dispersal storage function parameters comprises one or more of:

a pillars list;

a segmenting protocol;

a pre-slice data manipulation function;

a forward error correction encoding function;

a slicing pillar width;

a post-slice data manipulation function;

a write threshold; and

a read threshold.

6. The method of claim 5, wherein the pillars list comprises:

at least one set of pillar identifiers associated with less than a slicing pillar width number and at least the read threshold number of a plurality of DS units, wherein the at least one set of pillar identifiers is unique as compared to ever other set of pillar identifiers associated with previously determined playback error coding dispersal storage function parameter set for the recovered data.

7. A computer comprising:

an interface; and

a processing module operable to;

receive, via the interface, a first request to store a program;

determine first error coding dispersal storage function parameters;

encode a data segment of the program in accordance with the first error coding dispersal storage function parameters;

determine whether a second request to store the program is received;

encode a second data segment of the program in accordance with the first error coding dispersal storage function parameters when the second request is not received;

change the first error coding dispersal storage function parameters based on the another request to produce second error coding dispersal storage function parameters when the second request is received; and

encode the second data segment in accordance with the second error coding dispersal storage function parameters.

8. The computer of claim 7, wherein the processing module further functions to:

determine whether another request to store the program is received, wherein the another request is received, via the interface, in time, between the first and second requests;

determine whether to change the first error coding dispersal storage function parameters when the other request is received;

change the first error coding dispersal storage function parameters based on the other request to produce third error coding dispersal storage function parameters when the first error coding dispersal storage function parameters are to be changed; and

encoding another data segment in accordance with the third error coding dispersal storage function parameters.

9. The computer of claim 7, wherein the processing module further functions to change the first error coding dispersal storage function parameters based on the other request by:

changing a post-slice data manipulation function that includes at least one of;

an error injection function;

a bit dithering function;

a bit rotation function;

a slice comparison function;

a watermark function;

a hash function; and

a bit swapping function.

10. The computer of claim 7, wherein the processing module further functions to perform at least one of:

determining a first playback error coding dispersal storage function parameter set for a requesting device associated with the first request based on the first error coding dispersal storage function parameters and subsequent changes to the first error coding dispersal storage function parameters;

determining a second playback error coding dispersal storage function parameter set for a second requesting device associated with the second request based on the second error coding dispersal storage function parameters and subsequent changes to the second error coding dispersal storage function parameters;

outputting, via the interface, the first playback error coding dispersal storage function parameter set to the first requesting device; and

outputting, via the interface, the second playback error coding dispersal storage function parameter set to the second requesting device.

11. The computer of claim 7, wherein the first and second error coding dispersal storage function parameters comprises one or more of:

a pillars list;

a segmenting protocol;

a pre-slice data manipulation function;

a forward error correction encoding function;

a slicing pillar width;

a post-slice data manipulation function;

a write threshold; and

a read threshold.

12. The computer of claim 11, wherein the pillars list comprises:

at least one set of pillar identifiers associated with less than a slicing pillar width number and at least the read threshold number of a plurality of dispersed storage (DS) units, wherein the at least one set of pillar identifiers is unique as compared to every other set of pillar identifiers associated with previously determined playback error coding dispersal storage function parameter set for the recovered data.