SELECTING A DIRECTORY OF A DISPERSED STORAGE NETWORK

• US 20120226714A1
• 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: Resch, Jason K., Baptist, Andrew, Tsvetkov, Andrew
• Granted Patent: US 9,658,911 B2
• Time in Patent Office: Days
• US Class Current: 707/781
• 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 receiving a dispersed storage network (DSN) access request accessing DSN memory regarding a set of encoded data slices, selecting a local DSN directory or a global DSN directory to produce a selected DSN directory, identifying an entry of the selected DSN directory regarding the set of encoded data slices to produce an identified entry, and accessing the DSN memory regarding the set of encoded data slices. The method continues with the processing module determining whether to update one or more of the local DSN directory and the global DSN directory based on the accessing the DSN memory and when the one or more of the local DSN directory and the global DSN directory is to be updated, updating the one or more of the local DSN directory and the global DSN directory in accordance with the accessing the DSN memory.

Claims

1. A method comprises:

receiving a dispersed storage network (DSN) access request accessing DSN memory regarding a set of encoded data slices;

selecting a local DSN directory or a global DSN directory based on the DSN access request to produce a selected DSN directory;

identifying an entry of the selected DSN directory regarding the set of encoded data slices to produce an identified entry;

accessing the DSN memory regarding the set of encoded data slices based on information within the identified entry;

determining whether to update one or more of the local DSN directory and the global DSN directory based on the accessing the DSN memory; and

when the one or more of the local DSN directory and the global DSN directory is to be updated, updating the one or more of the local DSN directory and the global DSN directory in accordance with the accessing the DSN memory.

2. The method of claim 1, wherein the selecting the local DSN directory or the global DSN directory comprises:

identifying the local DSN directory from a plurality of local DSN directories based on a data identification code associated with the DSN access request;

identifying the global DSN directory from a plurality of global DSN directories based on the data identification code associated with the DSN access request;

selecting the selected DSN directory based on at least one of access type of the DSN access request, a DSN directory type indicator of the DSN access request, and requestor information of the DSN access request.

3. The method of claim 1, wherein the information within the identified entry comprises one or more of:

a data identifier;

a pathname;

a source name;

a set of slice names corresponding to the set of encoded data slices; and

a revision identifier.

4. The method of claim 1, wherein the determining whether to update the one or more of the local DSN directory and the global DSN directory comprises at least one of:

updating the global DSN directory when the access type is a write access request or a delete access request;

updating the global DSN directory and the local DSN directory when the access type is a write access request or a delete access request; and

updating the entry within the local DSN directory when a concurrency issues exists with a corresponding entry with the global DSN directory.

5. The method of claim 1, wherein the identifying the entry of the selected DSN directory comprises:

generating the entry when an access type is a write request, wherein the entry includes a data identifier and a source name.

6. The method of claim 1, wherein the updating the one or more of the local DSN directory and the global DSN directory further comprises:

deleting the entry from the local DSN directory and the global DSN directory when the access type is a delete request.

7. The method of claim 1, wherein the accessing the DSN memory further comprises:

performing a concurrency test between the entry of the local DSN directory and the entry of the global DSN directory; and

when a result of the concurrency test is unfavorable, accessing the DSN memory based on the information of the entry in the global DSN directory.

8. The method of claim 1 further comprises:

storing the local DSN directory in cache memory of a computing device executing the method; and

storing the global DSN directory in the DSN memory as a set of encoded directory slices.

9. A dispersed storage (DS) module comprises:

a first module operable to receive a dispersed storage network (DSN) access request accessing DSN memory regarding a set of encoded data slices;

a second module operable to select a local DSN directory or a global DSN directory based on the DSN access request to produce a selected DSN directory;

a third module operable to identify an entry of the selected DSN directory regarding the set of encoded data slices to produce an identified entry;

a fourth module operable to access the DSN memory regarding the set of encoded data slices based on information within the identified entry;

a fifth module operable to determine whether to update one or more of the local DSN directory and the global DSN directory based on the accessing the DSN memory; and

when the one or more of the local DSN directory and the global DSN directory is to be updated, a sixth module operable to update the one or more of the local DSN directory and the global DSN directory in accordance with the accessing the DSN memory.

10. The DS module of claim 9, wherein the second module functions to select the local DSN directory or the global DSN directory by:

identifying the local DSN directory from a plurality of local DSN directories based on a data identification code associated with the DSN access request;

identifying the global DSN directory from a plurality of global DSN directories based on the data identification code associated with the DSN access request;

selecting the selected DSN directory based on at least one of access type of the DSN access request, a DSN directory type indicator of the DSN access request, and requestor information of the DSN access request.

11. The DS module of claim 9, wherein the information within the identified entry comprises one or more of:

a data identifier;

a pathname;

a source name;

a set of slice names corresponding to the set of encoded data slices; and

a revision identifier.

12. The DS module of claim 9, wherein the fifth module functions to determine whether to update the one or more of the local DSN directory and the global DSN directory by at least one of:

updating the global DSN directory when the access type is a write access request or a delete access request;

updating the global DSN directory and the local DSN directory when the access type is a write access request or a delete access request; and

updating the entry within the local DSN directory when a concurrency issues exists with a corresponding entry with the global DSN directory.

13. The DS module of claim 9, wherein the third module functions to identify the entry of the selected DSN directory by:

generating the entry when an access type is a write request, wherein the entry includes a data identifier and a source name.

14. The DS module of claim 9, wherein the sixth module further functions to update the one or more of the local DSN directory and the global DSN directory by:

deleting the entry from the local DSN directory and the global DSN directory when the access type is a delete request.

15. The DS module of claim 9, wherein the fourth module further functions to access the DSN memory by:

performing a concurrency test between the entry of the local DSN directory and the entry of the global DSN directory; and

when a result of the concurrency test is unfavorable, accessing the DSN memory based on the information of the entry in the global DSN directory.

16. The DS module of claim 9 further comprises:

a seventh module operable to;

store the local DSN directory in cache memory of a computing device executing the method; and

store the global DSN directory in the DSN memory as a set of encoded directory slices.