RECOVERING AFFINITY WITH IMPOSTER SLICES

• US 20170123917A1
• Filed: 09/30/2016
• Published: 05/04/2017
• Est. Priority Date: 10/30/2015
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Baptist, Andrew D., Dhuse, Greg R., Khadiwala, Ravi V., Resch, Jason K., Volvovski, Ilya, Wozniak, Ethan S.
• Granted Patent: US 10,042,707 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 2201/805 Real-time
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0611 in relation to response time
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: H03M 13/1515 Reed-Solomon codes
• 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
• CPC Class Codes: H04L 43/0864 Round trip delays
• CPC Class Codes: H04L 43/0876 Network utilisation, e.g. volume of load or congestion level
• CPC Class Codes: H04L 43/16 Threshold monitoring
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• 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

Methods and apparatus for accessing dispersed storage error encoded data in a dispersed storage network (DSN). For each available primary storage unit, a processing module issues a write slice request including a slice name and encoded data slice corresponding to the primary storage unit where the encoded data slice includes an information dispersal algorithm (IDA) index of the primary storage unit. For each unavailable primary storage unit, the processing module issues a write imposter slice request to a foster storage unit that includes a slice name corresponding to foster storage unit and an imposter encoded data slice corresponding to the unavailable primary storage unit, where the imposter encoded data slice includes an IDA index corresponding to the unavailable primary storage unit. When the unavailable primary storage unit becomes available, the processing module facilitates transfer of the imposter encoded data slice to the newly available primary storage unit.

Claims

1. A method of accessing data in a dispersed storage network, the dispersed storage network including a plurality of primary dispersed storage units and a plurality of secondary dispersed storage units, the method comprising:

dispersed storage error encoding a data segment to produce a set of encoded data slices;

for each available primary dispersed storage unit of the plurality of primary dispersed storage units, sending a respective write slice request for receipt by a respective available primary dispersed storage unit, the respective write slice request including a respective slice name corresponding to the respective available primary dispersed storage unit and a respective encoded data slice of the set of encoded data slices, wherein the respective encoded data slice includes a first respective information dispersed algorithm index of the respective available primary dispersed storage unit; and

for each unavailable primary dispersed storage unit of the plurality of primary dispersed storage units, sending a respective write imposter slice request for receipt by a respective secondary dispersed storage unit of the plurality of secondary dispersed storage units, the respective write imposter slice request including a respective imposter slice name corresponding to the respective secondary dispersed storage unit and a respective imposter encoded data slice of the set of encoded data slices, wherein the respective imposter encoded data slice includes a second respective information dispersed algorithm index of the respective unavailable primary dispersed storage unit.

2. The method of claim 1, wherein the set of encoded data slices includes at least a write threshold number of encoded data slices.

3. The method of claim 2, wherein the plurality of primary dispersed storage units is equal to the number of encoded data slices in the set of encoded data slices.

4. The method of claim 1, further comprising sending a command to one of the respective secondary dispersed storage units to send one of the respective imposter encoded data slices to one of the respective unavailable primary dispersed storage units when the one of respective unavailable primary dispersed storage units becomes available.

5. The method of claim 4, further comprising sending a command to the one of the respective secondary dispersed storage units to delete the one of the respective imposter encoded data slices.

6. The method of claim 4, further comprising renaming the respective imposter encoded data slice.

7. The method of claim 1 further including receiving one of the respective imposter encoded data slices from one of the respective secondary dispersed storage units and forwarding the one of the respective imposter encoded data slices to one of the respective unavailable primary dispersed storage units when the one of the respective unavailable primary dispersed storage units becomes available.

8. The method of claim 7, further comprising sending a command to the one of the respective secondary dispersed storage units to delete the one of the respective imposter encoded data slices.

9. The method of claim 7, further comprising renaming the respective imposter encoded data slice.

10. A dispersed storage processing unit for use in a dispersed storage network, the dispersed storage network including a plurality of primary dispersed storage units and a plurality of secondary dispersed storage units, the first dispersed storage processing unit comprising:

a communications interface;

a memory; and

a processor;

wherein the memory includes a data segment and wherein the memory further includes instructions for causing the processor to;

dispersed storage error encode a data segment to produce a set of encoded data slices;

for each available primary dispersed storage unit of the plurality of primary dispersed storage units, send a respective write slice request for receipt by a respective available primary dispersed storage unit, the respective write slice request including a respective slice name corresponding to the respective available primary dispersed storage unit and a respective encoded data slice of the set of encoded data slices, wherein the respective encoded data slice includes a respective information dispersed algorithm index of the respective available primary dispersed storage unit; and

for each unavailable primary dispersed storage unit of the plurality of primary dispersed storage units, send a respective write imposter slice request for receipt by a respective secondary dispersed storage unit of the plurality of secondary dispersed storage units, the respective write imposter slice request including a respective imposter slice name corresponding to the respective secondary dispersed storage unit and a respective imposter encoded data slice of the set of encoded data slices, wherein the respective imposter encoded data slice includes a respective information dispersed algorithm index of the respective unavailable primary dispersed storage unit.

11. The dispersed storage processing unit of claim 10, wherein the set of encoded data slices includes at least a write threshold number of encoded data slices.

12. The dispersed storage processing unit of claim 11, wherein the plurality of primary dispersed storage units is equal to the number of encoded data slices in the set of encoded data slices.

13. The dispersed storage processing unit of claim 10, wherein the memory further includes instructions for causing the processor to send a command to one of the respective secondary dispersed storage unit to send one of the respective imposter encoded data slices to one of the respective unavailable primary dispersed storage units when the one of the respective unavailable primary dispersed storage units becomes available.

14. The dispersed storage processing unit of claim 13, wherein the memory further includes instructions for causing the processor to send a command to the one of the respective secondary dispersed storage units to delete one of the respective imposter encoded data slices.

15. The dispersed storage processing unit of claim 13, wherein the memory further includes instructions for causing the processor to rename the one of the respective imposter encoded data slices.

16. The dispersed storage processing unit of claim 10, wherein the memory further includes instructions for causing the processor to receive one of the respective imposter encoded data slices from one of the respective secondary dispersed storage units and forward the one of the respective imposter encoded data slices to one of the respective unavailable primary dispersed storage units when the one of the respective unavailable primary dispersed storage units becomes available.

17. The dispersed storage processing unit of claim 16, wherein the memory further includes instructions for causing the processor to send a command to the one of the respective secondary dispersed storage units to delete the one of the respective imposter encoded data slices.

18. The dispersed storage processing unit of claim 16, wherein the memory further includes instructions for causing the processor to rename the respective imposter encoded data slice.

19. A dispersed storage network comprising:

a plurality of primary dispersed storage units;

a plurality of secondary dispersed storage units; and

a dispersed storage processing unit, the dispersed storage processing unit including;

a communications interface;

a memory; and

a processor;

wherein the memory includes a data segment and wherein the memory further includes instructions for causing the processor to;

dispersed storage error encode a data segment to produce a set of encoded data slices;

for each available primary dispersed storage unit of the plurality of primary dispersed storage units, send a respective write slice request to a respective available primary dispersed storage unit, the respective write slice request including a respective slice name corresponding to the respective available primary dispersed storage unit and a respective encoded data slice of the set of encoded data slices, wherein the respective encoded data slice includes a respective information dispersed algorithm index of the respective available primary dispersed storage unit; and

for each unavailable primary dispersed storage unit of the plurality of primary dispersed storage units, send a respective write imposter slice request to a respective secondary dispersed storage unit of the plurality of secondary dispersed storage units, the respective write imposter slice request including a respective imposter slice name corresponding to the respective secondary dispersed storage unit and a respective imposter encoded data slice of the set of encoded data slices, wherein the respective imposter encoded data slice includes a respective information dispersed algorithm index of the respective unavailable primary dispersed storage unit.

20. The dispersed storage network of claim 19, wherein one of the respective secondary dispersed storage units periodically attempts to find one of the respective unavailable primary dispersed storage units.