Dispersed storage network utilizing revision snapshots

• US 8,352,501 B2
• Filed: 11/09/2010
• Issued: 01/08/2013
• Est. Priority Date: 01/28/2010
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Cleversafe Incorporated (International Business Machines Corporation)
• Inventors: Baptist, Andrew, Volvovski, Ilya, Leggette, Wesley
• Primary Examiner(s): HASAN, SYED HAROON
• Application Number:
  US12/942,990
• Publication Number:
  US 20110184912A1
• Time in Patent Office: 791 Days
• Field of Search: None
• US Class Current: 707/793
• 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 11/1448 Management of the data involved in backup or backup restore
• CPC Class Codes: G06F 16/182 Distributed file systems
• CPC Class Codes: G06F 16/184 implemented as replicated file system
• CPC Class Codes: G06F 16/1844 Management specifically adapted to replicated file systems
• CPC Class Codes: G06F 2201/805 Real-time
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: G06F 2211/1028 Distributed, i.e. distributed RAID systems with parity
• 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 begins by a processing module obtaining a directory file and determining a new snapshot identifier (ID) for the directory file. The method continues with the processing module identifying a version of a filename to associate with the new snapshot ID and updating the directory file by associating the snapshot ID to the version of the filename to produce an updated directory file. The method continues with the processing module dispersed storage error encoding the updated directory file to produce a set of encoded updated directory file slices and sending the set of encoded updated directory file slices to a dispersed storage network (DSN) memory for storage.

Claims

1. A method comprises:

obtaining a directory file that includes a plurality of entries, wherein an entry of the plurality of entries includes a file or directory name field, distributed storage network (DSN) information field, and a snapshot list field;

determining a new snapshot identifier (ID) regarding a file;

updating the directory file to produce an updated directory file, wherein the updating includes;

creating a new entry within the file directory for the file;

when one or more of the plurality of entries corresponds to the file, maintaining information of the file or directory name, the DSN information field, and the snapshot list field;

for each remaining entry of the plurality of entries, updating the snapshot list field to include the new snapshot ID;

dispersed storage error encoding the updated directory file to produce a set of encoded updated directory file slices; and

sending the set of encoded updated directory file slices to a dispersed storage network (DSN) memory for storage.

2. The method of claim 1, wherein the determining the new snapshot ID further

comprises at least one of:

receiving a command to produce the new snapshot ID;

accessing a lookup table at a given time to produce the new snapshot ID;

producing the new snapshot ID at an expiration of a period of time since producing a previous snapshot ID;

producing the new snapshot ID when a change occurs to the file; and

producing the new snapshot ID when a change occurs to a file name associated with the file.

3. The method of claim 1 further comprises:

the file or directory name field including one or more of a file name, a directory name, and a directory path;

the DSN information field including one or more of a block number, a size indicator, a DSN address, and a revision number, and

a snapshot list field including a list of snapshots.

4. The method of claim 1, wherein obtaining the directory file comprises:

retrieving a set of encoded directory file slices from the DSN memory based on a directory file DSN address; and

dispersed storage error decoding the set of encoded directory file slices to reproduce the directory file.

5. The method of claim 1, wherein the new snapshot ID comprises at least one of:

a predetermined value;

a value based on a previous snapshot ID;

a value based on a user ID; and

a value based on a vault ID.

6. The method of claim 1 further comprises:

updating a vault snapshot file to associate the new snapshot ID with at least one previous snapshot ID to produce an updated vault snapshot file;

dispersed storage error encoding the updated vault snapshot file to produce a set of encoded updated vault snapshot file slices; and

sending the set of encoded updated vault snapshot file slices to the DSN memory for storage.

7. A computer comprises:

an interface; and

a processing module operable to;

obtain a directory file that includes a plurality of entries, wherein an entry of the plurality of entries includes a file or directory name field, distributed storage network (DSN) information field, and a snapshot list field;

determine a new snapshot identifier (ID) regarding a file;

update the directory file to produce an updated directory file, wherein the updating includes;

creating a new entry within the file directory for the file;

when one or more of the plurality of entries corresponds to the file, maintaining information of the file or directory name, the DSN information field, and the snapshot list field;

for each remaining entry of the plurality of entries, updating the snapshot list field to include the new snapshot ID;

dispersed storage error encode the updated directory file to produce a set of encoded updated directory file slices; and

send, via the interface, the set of encoded updated directory file slices to a dispersed storage network (DSN) memory for storage.

8. The computer of claim 7, wherein the processing module further functions to determine the new snapshot ID by at least one of:

receiving, via the interface, a command to produce the new snapshot ID;

accessing a lookup table at a given time to produce the new snapshot ID;

producing the new snapshot ID at an expiration of a period of time since producing a previous snapshot ID;

producing the new snapshot ID when a change occurs to the file; and

producing the new snapshot ID when a change occurs to a file name of the file.

9. The computer of claim 7 further comprises:

the file or directory name field including one or more of a file name, a directory name, and a directory path;

the DSN information field including one or more of a block number, a size indicator, a DSN address, and a revision number, and

a snapshot list field including a list of snapshots.

10. The computer of claim 7, wherein the processing module further functions to obtain the directory file by:

retrieving, via the interface, a set of encoded directory file slices from the DSN memory based on a directory file DSN address; and

dispersed storage error decoding the set of encoded directory file slices to reproduce the directory file.

11. The computer of claim 7, wherein the new snapshot ID comprises at least one of:

a predetermined value;

a value based on a previous snapshot ID;

a value based on a user ID; and

a value based on a vault ID.

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

update a vault snapshot file to associate the new snapshot ID with at least one previous snapshot ID to produce an updated vault snapshot file;

dispersed storage error encode the updated vault snapshot file to produce a set of encoded updated vault snapshot file slices; and

send, via the interface, the set of encoded updated vault snapshot file slices to the DSN memory for storage.