MAINTAINING DATA CONCURRENCY WITH A DISPERSED STORAGE NETWORK

• US 20120226933A1
• Filed: 02/14/2012
• Published: 09/06/2012
• Est. Priority Date: 03/02/2011
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Cleversafe Incorporated (International Business Machines Corporation)
• Inventors: Baptist, Andrew, Leggette, Wesley, Volvovski, Ilya, Resch, Jason K.
• Granted Patent: US 9,183,073 B2
• Time in Patent Office: Days
• US Class Current: 714/6.2
• CPC Class Codes: G06F 11/0727 in a storage system, e.g. in a DASD or network based storage system drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; 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], H04L67/1097
• CPC Class Codes: G06F 11/0757 by exceeding a time limit, i.e. time-out, e.g. watchdogs
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 2211/1028 Distributed, i.e. distributed RAID systems with parity

Abstract

A method begins by a processing module generating a transaction number and generating at least a threshold number of dispersed storage network (DSN) concurrency requests, wherein each of the at least the threshold number of DSN concurrency requests includes a header section and a payload section; each of the payload sections includes the transaction number, a last known slice revision number, and a slice name section, wherein a first slice name section of a first one of the payload sections includes one or more first slice names that includes a first slice name corresponding to a first encoded data slice of a set of encoded data slices; and a second slice name section of a second one of the payload sections includes one or more second slice names that includes a second slice name corresponding to a second encoded data slice of the set of encoded data slices.

Claims

1. A method for a dispersed storage network (DSN) client to maintain concurrency of data with a DSN memory, wherein a segment of the data is encoded into a set of encoded data slices using a dispersed storage error coding function and the set of encoded data slices is stored in the DSN memory, the method comprises:

generating a transaction number; and

generating at least a threshold number of DSN concurrency requests, wherein;

each of the at least the threshold number of DSN concurrency requests includes a header section and a payload section; and

each of the payload sections includes the transaction number, a last known slice revision number, and a slice name section, wherein;

a first slice name section of a first one of the payload sections includes one or more first slice names that includes a first slice name corresponding to a first encoded data slice of the set of encoded data slices; and

a second slice name section of a second one of the payload sections includes one or more second slice names that includes a second slice name corresponding to a second encoded data slice of the set of encoded data slices.

2. The method of claim 1, wherein each of the header sections comprises:

a payload length field and at least one of an operation code field, a protocol class field, and a protocol class version field, wherein;

a first payload length field of a first one of the header sections includes a first payload length of the first one of the payload sections;

a second payload length field of a second one of the header sections includes a second payload length of the second one of the payload sections;

each of the operation code fields includes a concurrency request operation code;

each of the protocol class fields includes a protocol class for the concurrency request operation code; and

each of the protocol class version fields includes a version of the concurrency request operation code.

3. The method of claim 1 further comprises:

outputting, in order, the header section, the transaction number, the slice name section, and the last known slice revision number of the payload section for each of the at least the threshold number of DSN concurrency requests.

4. The method of claim 1 further comprises:

generating the last known revision number by at least one of;

selecting the last known revision number from a revision number list;

obtaining the last known revision number as a revision number associated with a copy of the data;

extracting the last known slice revision number from a list range response message;

extracting the last known slice revision number from a concurrency response message; and

extracting the last known slice revision number from a read response message.

5. The method of claim 1, wherein the generating the transaction number comprises:

obtaining a clock value;

multiplying the clock value by a predetermined multiplier to produce an expanded clock value; and

summing the expanded clock value and a random number to produce the value, wherein a number of digits of the random number is substantially the same as a number of digits of the predetermined multiplier.

6. A method comprises:

receiving one of at least a threshold number of dispersed storage network (DSN) concurrency requests that includes a header section and a payload section, wherein the payload section includes a transaction number, a last known slice revision number, and a slice name section; and

in response to the one of at least the threshold number of DSN concurrency requests;

determining a most recent slice revision number based on a slice name contained in the slice name section;

when the most recent slice revision number substantially matches the last known revision number;

generating a DSN concurrency response to include a header section and a payload section, wherein the payload section includes a revision match status indication and a slice revision count regarding the slice name; and

when the most recent slice revision number does not substantially match the last known revision number;

generating the DSN concurrency response to include the header section and the payload section, wherein the payload section includes a revision mismatch status indication, the slice revision count regarding the slice name, one or more slice revision numbers corresponding to the slice name, one or more slice lengths corresponding to the slice name, and one or more encoded data slices corresponding to the slice name.

7. The method of claim 6, wherein the header section comprises:

a payload length field and at least one of an operation code field, a protocol class field, and a protocol class version field, wherein;

the payload length field includes a length of the payload section;

the operation code field includes a concurrency response operation code;

the protocol class field includes a protocol class for the concurrency response operation code; and

the protocol class version field includes a version of the concurrency response operation code.

8. The method of claim 6 further comprises:

determining when an error condition exists based on one or more of;

the slice name being associated with a locked encoded data slice state, a transaction number error, the slice name is associated with one or more encoded data slices that are unavailable, and one of at least the threshold number of DSN concurrency requests is not authorized; and

discarding the DSN concurrency response when the error condition exists.

9. A dispersed storage (DS) module of a dispersed storage network (DSN) client is operable to maintain concurrency of data with a DSN memory, wherein a segment of the data is encoded into a set of encoded data slices using a dispersed storage error coding function and the set of encoded data slices is stored in the DSN memory, the module comprises:

a first module operable to generate a transaction number; and

a second module operable to generate at least a threshold number of DSN concurrency requests, wherein;

each of the at least the threshold number of DSN concurrency requests includes a header section and a payload section; and

each of the payload sections includes the transaction number, a last known slice revision number, and a slice name section, wherein;

a first slice name section of a first one of the payload sections includes one or more first slice names that includes a first slice name corresponding to a first encoded data slice of the set of encoded data slices; and

a second slice name section of a second one of the payload sections includes one or more second slice names that includes a second slice name corresponding to a second encoded data slice of the set of encoded data slices.

10. The DS module of claim 9, wherein each of the header sections comprises:

a payload length field and at least one of an operation code field, a protocol class field, and a protocol class version field, wherein;

a first payload length field of a first one of the header sections includes a first payload length of the first one of the payload sections;

a second payload length field of a second one of the header sections includes a second payload length of the second one of the payload sections;

each of the operation code fields includes a concurrency request operation code;

each of the protocol class fields includes a protocol class for the concurrency request operation code; and

each of the protocol class version fields includes a version of the concurrency request operation code.

11. The DS module of claim 9 further comprises:

a third module operable to output, in order, the header section, the transaction number, the slice name section, and the last known slice revision number of the payload section for each of the at least the threshold number of DSN concurrency requests.

12. The DS module of claim 9 further comprises:

a fourth module operable to generate the last known revision number by at least one of;

selecting the last known revision number from a revision number list;

obtaining the last known revision number as a revision number associated with a copy of the data;

extracting the last known slice revision number from a list range response message;

extracting the last known slice revision number from a concurrency response message; and

extracting the last known slice revision number from a read response message.

13. The DS module of claim 9, wherein the first module is further operable to generate the transaction number by:

obtaining a clock value;

multiplying the clock value by a predetermined multiplier to produce an expanded clock value; and

summing the expanded clock value and a random number to produce the value, wherein a number of digits of the random number is substantially the same as a number of digits of the predetermined multiplier.

14. A dispersed storage (DS) unit comprises:

a first module operable to receive one of at least a threshold number of dispersed storage network (DSN) concurrency requests that includes a header section and a payload section, wherein the payload section includes a transaction number, a last known slice revision number, and a slice name section; and

in response to the one of at least the threshold number of DSN concurrency requests;

a second module operable to determine a most recent slice revision number based on a slice name contained in the slice name section;

when the most recent slice revision number substantially matches the last known revision number;

a third module operable to generate a DSN concurrency response to include a header section and a payload section, wherein the payload section includes a revision match status indication and a slice revision count regarding the slice name; and

when the most recent slice revision number does not substantially match the last known revision number;

the third module operable to generating the DSN concurrency response to include the header section and the payload section, wherein the payload section includes a revision mismatch status indication, the slice revision count regarding the slice name one or more slice revision numbers corresponding to the slice name, one or more slice lengths corresponding to the slice name, and one or more encoded data slices corresponding to the slice name.

15. The DS unit of claim 14, wherein the header section comprises:

a payload length field and at least one of an operation code field, a protocol class field, and a protocol class version field, wherein;

the payload length field includes a length of the payload section;

the operation code field includes a concurrency response operation code;

the protocol class field includes a protocol class for the concurrency response operation code; and

the protocol class version field includes a version of the concurrency response operation code.

16. The DS unit of claim 14 further comprises:

a fourth module operable to;

determine when an error condition exists based on one or more of;

the slice name being associated with a locked encoded data slice state, a transaction number error, the slice name is associated with one or more encoded data slices that are unavailable, and one of at least the threshold number of DSN concurrency requests is not authorized; and

discard the DSN concurrency response when the error condition exists.