Adjusting data dispersal in a dispersed storage network

• US 8,627,178 B2
• Filed: 07/19/2013
• Issued: 01/07/2014
• Est. Priority Date: 03/16/2010
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Cleversafe Incorporated (International Business Machines Corporation)
• Inventors: Clifone, Bart, Resch, Jason K., Gladwin, S. Christopher
• Primary Examiner(s): Ehne, Charles
• Application Number:
  US13/946,136
• Publication Number:
  US 20130311851A1
• Time in Patent Office: 172 Days
• Field of Search: 714/751, 714/752, 714/763, 714/770
• US Class Current: 714/763
• 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 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 2211/1028 Distributed, i.e. distributed RAID systems with parity
• CPC Class Codes: H03M 13/35 Unequal or adaptive error protection, e.g. by providing a different level of protection according to significance of source information or by adapting the coding according to the change of transmission channel characteristics
• 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

Abstract

A method begins with a processing module determining that storage of data requires updating, wherein the data is stored as a plurality of sets of encoded data slices in DSN memory. For a first type of updating, the processing module increases the total number while maintaining the decode threshold number. The processing module then, for each set of encoded data slices, creates another encoded data slice in accordance with the dispersed storage error encoding function and the increased total number and sends the new encoded data slices to the DSN memory. For a second type of updating, the processing module increases the total number and the decode threshold number. The processing module then recovers the data and encodes it in accordance with the dispersed storage error encoding function using the increased total number and the increased decode threshold number to produce an updated plurality of sets of encoded data slices.

Claims

1. A method for execution by a processing module of a computing device of a distributed storage network (DSN) device, the method comprises:

determining that storage of data requires updating, wherein the data is encoded in accordance with a dispersed storage error encoding function using dispersed storage error encoding parameters to produce a plurality of sets of encoded data slices, which is stored in memory of the DSN, wherein the dispersed storage error encoding parameters includes a total number of encoded data slices per set of encoded data slices and a decode threshold number of encoded data slices that are required from a set of encoded data slices to recover a data segment of the data;

for a first type of updating of the storage of the data;

increasing the total number while maintaining the decode threshold number;

for each of the sets of encoded data slices of the plurality of sets of encode data slices;

creating at least one more encoded data slice in accordance with the dispersed storage error encoding function and the increased total number; and

sending the at least one more encoded data slice to the memory of the DSN for storage therein; and

for a second type of updating of the storage of the data;

increasing the total number and increasing the decode threshold number;

recovering the data from retrieved encoded data slices of the plurality of sets of encoded data slices;

encoding the recovered data in accordance with the dispersed storage error encoding function using the increased total number and the increased decode threshold number to produce an updated plurality of sets of encoded data slices; and

sending the updated plurality of sets of encoded data slices to the memory of the DSN for storage therein.

2. The method of claim 1, wherein the determining that storage of data requires updating comprises one of:

determining under performance of the DSN with respect to accessing the plurality of sets of encoded data slices; and

determining over performance of the DSN with respect to accessing the plurality of sets of encoded data slices.

3. The method of claim 1 further comprises:

for a third type of updating of the storage of the data;

decreasing the total number while maintaining the decode threshold number;

for each of the sets of encoded data slices of the plurality of sets of encode data slices;

selecting at least one encoded data slice based on the decreased total number and the total number; and

deleting the selected at least one encoded data slice from the memory of the DSN.

4. The method of claim 1 further comprises:

for a third type of updating of the storage of the data;

decreasing the decode threshold number and maintaining the total number;

recovering the data from retrieved encoded data slices of the plurality of sets of encoded data slices;

encoding the recovered data in accordance with the dispersed storage error encoding function using the total number and the decreased decode threshold number to produce another updated plurality of sets of encoded data slices; and

sending the other updated plurality of sets of encoded data slices to the memory of the DSN for storage therein.

5. The method of claim 1 further comprises:

for a third type of updating of the storage of the data;

decreasing the decode threshold number and decreasing the total number;

recovering the data from retrieved encoded data slices of the plurality of sets of encoded data slices;

encoding the recovered data in accordance with the dispersed storage error encoding function using the decreased total number and the decreased decode threshold number to produce another updated plurality of sets of encoded data slices; and

sending the other updated plurality of sets of encoded data slices to the memory of the DSN for storage therein.

6. The method of claim 1 further comprises:

determining the type of updating based on a comparison of a performance based indication with a performance threshold.

7. The method of claim 1 further comprises:

for each of the at least one more encoded data slice created for the first type of updating of the storage of the data;

creating a slice name to links the at least one more encoded data slice to a correspond set of encoded data slices of the plurality of sets of encoded data slices; and

updating a storage location table to include the slices names.

8. The method of claim 1, wherein the sending the at least one more encoded data slice to the memory of the DSN comprises:

identifying storage units of the DSN that are storing the plurality of sets of encoded data slices;

selecting at least one more storage unit of the DSN; and

sending the at least one more encoded data slice of each of the plurality of sets of encoded data slices to the selected at least one more storage unit.

9. The method of claim 1, wherein the sending the updated plurality of sets of encoded data slices to the memory of the DSN comprises:

selecting storage units of the DSN; and

sending the updated plurality of sets of encoded data slices to the selected storage units.

10. A computer comprises:

an interface;

a memory; and

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

determine that storage of data requires updating, wherein the data is encoded in accordance with a dispersed storage error encoding function using dispersed storage error encoding parameters to produce a plurality of sets of encoded data slices, which is stored in memory of the DSN, wherein the dispersed storage error encoding parameters includes a total number of encoded data slices per set of encoded data slices and a decode threshold number of encoded data slices that are required from a set of encoded data slices to recover a data segment of the data;

for a first type of updating of the storage of the data;

increase the total number while maintaining the decode threshold number;

for each of the sets of encoded data slices of the plurality of sets of encode data slices;

create at least one more encoded data slice in accordance with the dispersed storage error encoding function and the increased total number; and

send, via the interface, the at least one more encoded data slice to the memory of the DSN for storage therein; and

for a second type of updating of the storage of the data;

increase the total number and increasing the decode threshold number;

recover the data from retrieved encoded data slices of the plurality of sets of encoded data slices;

encode the recovered data in accordance with the dispersed storage error encoding function using the increased total number and the increased decode threshold number to produce an updated plurality of sets of encoded data slices; and

send, via the interface, the updated plurality of sets of encoded data slices to the memory of the DSN for storage therein.

11. The computer of claim 10, wherein the processing module is further operable to determine that storage of data requires updating by one of:

determining under performance of the DSN with respect to accessing the plurality of sets of encoded data slices; and

determining over performance of the DSN with respect to accessing the plurality of sets of encoded data slices.

12. The computer of claim 10, wherein the processing module is further operable to:

for a third type of updating of the storage of the data;

decrease the total number while maintaining the decode threshold number;

for each of the sets of encoded data slices of the plurality of sets of encode data slices;

select at least one encoded data slice based on the decreased total number and the total number; and

delete the selected at least one encoded data slice from the memory of the DSN.

13. The computer of claim 10, wherein the processing module is further operable to:

for a third type of updating of the storage of the data;

decrease the decode threshold number and maintaining the total number;

recover the data from retrieved encoded data slices of the plurality of sets of encoded data slices;

encode the recovered data in accordance with the dispersed storage error encoding function using the total number and the decreased decode threshold number to produce another updated plurality of sets of encoded data slices; and

send, via the interface, the other updated plurality of sets of encoded data slices to the memory of the DSN for storage therein.

14. The computer of claim 10, wherein the processing module is further operable to:

for a third type of updating of the storage of the data;

decrease the decode threshold number and decreasing the total number;

recover the data from retrieved encoded data slices of the plurality of sets of encoded data slices;

encode the recovered data in accordance with the dispersed storage error encoding function using the decreased total number and the decreased decode threshold number to produce another updated plurality of sets of encoded data slices; and

send, via the interface, the other updated plurality of sets of encoded data slices to the memory of the DSN for storage therein.

15. The computer of claim 10, wherein the processing module is further operable to:

determine the type of updating based on a comparison of a performance based indication with a performance threshold.

16. The computer of claim 10, wherein the processing module is further operable to:

for each of the at least one more encoded data slice created for the first type of updating of the storage of the data;

create a slice name to links the at least one more encoded data slice to a correspond set of encoded data slices of the plurality of sets of encoded data slices; and

update a storage location table to include the slices names.

17. The computer of claim 10, wherein the processing module is further operable to send the at least one more encoded data slice to the memory of the DSN by:

identifying storage units of the DSN that are storing the plurality of sets of encoded data slices;

selecting at least one more storage unit of the DSN; and

sending, via the interface, the at least one more encoded data slice of each of the plurality of sets of encoded data slices to the selected at least one more storage unit.

18. The computer of claim 10, wherein the processing module is further operable to send the updated plurality of sets of encoded data slices to the memory of the DSN by:

selecting storage units of the DSN; and

sending, via the interface, the updated plurality of sets of encoded data slices to the selected storage units.