ACCESSING DATA STORED IN A DISPERSED STORAGE MEMORY

• US 20140108890A1
• Filed: 12/16/2013
• Published: 04/17/2014
• Est. Priority Date: 06/22/2010
• 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 9,684,558 B2
• Time in Patent Office: Days
• US Class Current: 714/769
• CPC Class Codes: G06F 11/10 Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/3409 for performance assessment
• CPC Class Codes: G06F 2211/1028 Distributed, i.e. distributed RAID systems with parity
• 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 13/1515 Reed-Solomon codes
• CPC Class Codes: H03M 13/23 using convolutional codes, e.g. unit memory codes
• CPC Class Codes: H03M 13/353 Adaptation to the channel
• CPC Class Codes: H03M 13/3761 using code combining, i.e. using combining of codeword portions which may have been transmitted separately, e.g. Digital Fountain codes, Raptor codes or Luby Transform [LT] codes

Abstract

A method begins by a processing module forward error correction (FEC) encoding data to produce FEC encoded data and dividing the FEC encoded data into a set of FEC encoded words. The method continues with the processing module generating integrity information based on the data and generating a word name for an FEC encoded word of the set of FEC encoded words. The method continues with the processing module affiliating an address of allocated address space of a dispersed storage memory with the word name and storing the integrity information, the word name, and the address. The method continues with the processing module creating a write command to store the FEC encoded word at the address in the dispersed storage memory.

Claims

1. A method for execution by a processing module, the method comprises:

retrieving, for data, integrity information and a set of addresses;

creating a set of read commands to retrieve a set of forward error correction (FEC) encoded words from the set of addresses in a dispersed storage memory;

when at least a decode threshold number of the FEC encoded words are retrieved;

combining the at least a decode threshold number of the FEC encoded words to produce FEC encoded data; and

FEC decoding the FEC encoded data to produce recaptured data;

generating recaptured integrity information based on the recaptured data;

comparing the recaptured integrity information with the integrity information; and

when the comparing is favorable, indicating that the recaptured data is valid.

2. The method of claim 1 further comprises:

identifying a set of word names based on the data; and

utilizing the set of word names to index a table to retrieve the integrity information and the set of addresses.

3. The method of claim 1, wherein the dispersed storage memory comprises at least one of:

a local memory of a device executing the method;

a memory of a storage service provider; and

a network coupled memory unit.

4. The method of claim 1, wherein the generating the recaptured integrity information comprises at least one of:

performing a hash algorithm on the recaptured data to produce the integrity information;

performing a hash-based message authentication code (HMAC) on the recaptured data to produce the integrity information;

performing a parity function on the recaptured data to produce the integrity information;

performing a cyclic redundancy check function on the recaptured data to produce the integrity information; and

performing a mask generating function (MGT) on the recaptured data to produce the integrity information.

5. A computer comprises:

an interface;

a memory; and

a processing module operably coupled to the interface and the memory, wherein the processing module is operable to;

retrieve, for data, via interface, integrity information and a set of addresses;

create a set of read commands to retrieve a set of forward error correction (FEC) encoded words from the set of addresses in a dispersed storage memory;

when at least a decode threshold number of the FEC encoded words are retrieved;

combine the at least a decode threshold number of the FEC encoded words to produce FEC encoded data; and

FEC decode the FEC encoded data to produce recaptured data;

generate recaptured integrity information based on the recaptured data;

compare the recaptured integrity information with the integrity information; and

when the comparing is favorable, indicate that the recaptured data is valid.

6. The computer of claim 5, wherein the processing module further functions to:

identify a set of word names based on the data; and

utilize the set of word names to index a table to retrieve the integrity information and the set of addresses.

7. The computer of claim 5, wherein the dispersed storage memory comprises at least one of:

a local memory of a device executing the method;

a memory of a storage service provider; and

a network coupled memory unit.

8. The computer of claim 5, wherein the processing module functions to generate the recaptured integrity information by at least one of:

performing a hash algorithm on the recaptured data to produce the integrity information;

performing a hash-based message authentication code (HMAC) on the recaptured data to produce the integrity information;

performing a parity function on the recaptured data to produce the integrity information;

performing a cyclic redundancy check function on the recaptured data to produce the integrity information; and

performing a mask generating function (MGT) on the recaptured data to produce the integrity information.