Proxying read requests when performance or availability failure is anticipated

• US 10,146,458 B2
• Filed: 03/23/2017
• Issued: 12/04/2018
• Est. Priority Date: 03/29/2016
• Status: Active Grant

• Current Assignee: Green Market Square Limited
• Original Assignee: International Business Machines Corporation
• Inventors: Baptist, Andrew D., Dhuse, Greg R., Khadiwala, Ravi V., Wozniak, Ethan S.
• Primary Examiner(s): Nguyen, Steve N
• Application Number:
  US15/467,256
• Publication Number:
  US 20170288696A1
• Time in Patent Office: 621 Days
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G06F 21/31 User authentication
• CPC Class Codes: G06F 2221/2133 Verifying human interaction, e.g., Captcha
• 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 3/0631 by allocating resources to storage systems
• 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 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• 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 8/65 Updates security arrangements therefor G06F21/57
• CPC Class Codes: G06F 9/485 Task life-cycle, e.g. stopping, restarting, resuming execution G06F9/4881 takes precedence
• CPC Class Codes: G06F 9/4881 Scheduling strategies for dispatcher, e.g. round robin, multi-level priority queues
• CPC Class Codes: H03M 13/05 using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits H03M13/2906 takes precedence
• CPC Class Codes: H03M 13/1515 Reed-Solomon codes
• CPC Class Codes: H03M 13/373 : with erasure correction and erasure determination, e.g. for packet loss recovery or setting of erasures for the decoding of Reed-Solomon codes
• CPC Class Codes: H03M 13/616 : Matrix operations, especially for generator matrices or check matrices, e.g. column or row permutations
• CPC Class Codes: H04L 61/10 : of different types
• CPC Class Codes: H04L 61/50 : Address allocation
• CPC Class Codes: H04L 63/08 : for authentication of entities cryptographic mechanisms or cryptographic arrangements for entity authentication H04L9/32
• CPC Class Codes: H04L 63/104 : Grouping of entities
• CPC Class Codes: H04L 63/108 : when the policy decisions are valid for a limited amount of time
• 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]
• CPC Class Codes: H04L 67/56 : Provisioning of proxy services store-and-forward switching systems in data switching networks H04L12/54

Abstract

A method includes receiving, by a read threshold number of storage units of a dispersed storage network (DSN), the read threshold number of read requests regarding the read threshold number of encoded data slices of a set of encoded data slices. The method further includes determining, by each storage unit of the read threshold number of storage units, whether the storage unit is capable of processing a respective read request. When a particular storage unit is not capable of processing the respective read request, the method further includes sending, by the particular storage unit, a proxy read request to another storage unit that is not in the read threshold number of storage units. The method further includes determining, by the other storage unit, whether the other storage unit is capable of processing the proxy read request and, when it is, processing the proxy read request.

Claims

1. A method comprises:

receiving, by a read threshold number of storage units of a set of storage units of a dispersed storage network (DSN), a read threshold number of read requests regarding a read threshold number of encoded data slices of a set of encoded data slices, wherein a data segment of a data object is dispersed storage error encoded into the set of encoded data slices, wherein the set of encoded data slices is stored in the set of storage units, and wherein the read threshold number is less than a total number of encoded data slices in the set of encoded data slices and is equal to or greater than a decode threshold number;

determining, by each storage unit of the read threshold number of storage units, whether the storage unit is capable of processing a respective read request of the read threshold number of read requests;

when a particular storage unit of the read threshold number of storage units is not capable of processing the respective read request;

sending, by the particular storage unit, a proxy read request to another storage unit of the set of storage units that is not in the read threshold number of storage units;

determining, by the other storage unit, whether the other storage unit is capable of processing the proxy read request; and

when the other storage unit is capable of processing the proxy read request, processing, by the other storage unit, the proxy read request.

2. The method of claim 1, wherein the determining whether the storage unit is capable of processing the respective read request comprises one or more of:

determining that the storage unit does not currently store an encoded data slice identified in the respective read request;

determining that the encoded data slice identified in the respective read request is stored in a memory device of the particular storage unit that is currently unavailable; and

determining that processing of the respective read request would exceed a response time threshold.

3. The method of claim 1 further comprises:

identifying, by the particular storage unit, the other storage unit based on one or more of;

an indication within the respective read request;

the read threshold number of read requests including slice names that identified the read threshold number of encoded data slices;

by executing a distributed agreement protocol function; and

by a look up table.

4. The method of claim 1, wherein the processing of the proxy read request comprises:

retrieving, by the other storage unit, from a local memory another encoded data slice of the set of encoded data slices that was not included in the read threshold number of encoded data slices; and

sending, by the other storage unit, the other encoded data slice to a requesting computing device.

5. The method of claim 1, wherein the processing of the proxy read request comprises:

retrieving, by the other storage unit, from a local memory another encoded data slice of the set of encoded data slices that was not included in the read threshold number of encoded data slices;

sending, by the other storage unit, the other encoded data slice to the particular storage unit; and

forwarding, by the particular storage unit, the other encoded data slice to a requesting computing device.

6. The method of claim 1 further comprises:

notifying, by the particular storage unit or the other storage unit, a requesting computing device of the proxy read request.

7. The method of claim 1 further comprises:

when the other storage unit is not capable of processing the proxy read request;

sending, by the other storage unit, the proxy read request to yet another storage unit of the set of storage units that is not in the read threshold number of storage units;

determining, by the yet another storage unit, whether the yet another storage unit is capable of processing the proxy read request; and

when the yet another storage unit is capable of processing the proxy read request, processing, by the yet another storage unit, the proxy read request.

8. The method of claim 7 further comprises:

notifying, by the particular storage unit, the other storage unit, or the yet another storage unit, a requesting computing device of the proxy read request being processed by the yet another storage unit.

9. A computer readable memory device comprises:

a first memory section that stores operational instructions that, when executed by a read threshold number of storage units of a set of storage units of a dispersed storage network (DSN), causes the read threshold number of storage units to;

receive a read threshold number of read requests regarding a read threshold number of encoded data slices of a set of encoded data slices, wherein a data segment of a data object is dispersed storage error encoded into the set of encoded data slices, wherein the set of encoded data slices is stored in the set of storage units, and wherein the read threshold number is less than a total number of encoded data slices in the set of encoded data slices and is equal to or greater than a decode threshold number;

a second memory section that stores operational instructions that, when executed by each storage unit of the read threshold number of storage units, causes each storage unit of the read threshold number of storage units to;

determine whether the storage unit is capable of processing a respective read request of the read threshold number of read requests;

a third memory section that stores operational instructions that, when executed by a particular storage unit of the read threshold number of storage units, causes the particular storage unit to;

send a proxy read request to another storage unit of the set of storage units that is not in the read threshold number of storage units when the particular storage unit is not capable of processing the respective read request;

a fourth memory section that stores operational instructions that, when executed by the other storage unit, causes the other storage unit to;

determine whether the other storage unit is capable of processing the proxy read request; and

when the other storage unit is capable of processing the proxy read request, process the proxy read request.

10. The computer readable memory device of claim 9, wherein the second memory section further stores operational instructions that, when executed by each storage unit of the read threshold number of storage units, causes each storage unit of the read threshold number of storage units to determine whether the storage unit is capable of processing the respective read request by one or more of:

determining that the storage unit does not currently store an encoded data slice identified in the respective read request;

determining that the encoded data slice identified in the respective read request is stored in a memory device of the particular storage unit that is currently unavailable; and

determining that processing of the respective read request would exceed a response time threshold.

11. The computer readable memory device of claim 9, wherein the third memory section further stores operational instructions that, when executed by the particular storage unit, causes the particular storage unit to:

identifying, by the particular storage unit, the other storage unit based on one or more of;

an indication within the respective read request;

the read threshold number of read requests including slice names that identified the read threshold number of encoded data slices;

by executing a distributed agreement protocol function; and

by a look up table.

12. The computer readable memory device of claim 9, wherein the fourth memory section that stores operational instructions that, when executed by the other storage unit, causes the other storage unit to process the proxy read request by:

retrieving from a local memory another encoded data slice of the set of encoded data slices that was not included in the read threshold number of encoded data slices; and

sending, by the other storage unit, the other encoded data slice to a requesting computing device.

13. The computer readable memory device of claim 9 further comprises:

the fourth memory section further stores operational instructions that, when executed by the other storage unit, causes the other storage unit to process the proxy read request by;

retrieving from a local memory another encoded data slice of the set of encoded data slices that was not included in the read threshold number of encoded data slices;

sending the other encoded data slice to the particular storage unit; and

the third memory section further stores operational instructions that, when executed by the particular storage unit, causes the particular storage unit to;

forward the other encoded data slice to a requesting computing device.

14. The computer readable memory device of claim 9, wherein the third or fourth memory section further stores operational instructions that, when executed by the particular storage unit or the other storage unit, causes the particular storage unit or the other storage unit to:

notify a requesting computing device of the proxy read request.

15. The computer readable memory device of claim 9 further comprises:

the fourth memory section further stores operational instructions that, when executed by the other storage unit, causes the other storage unit to;

send the proxy read request to yet another storage unit of the set of storage units that is not in the read threshold number of storage units when the other storage unit is not capable of processing the proxy read request;

a fifth memory section that stores operational instructions that, when executed by the yet another storage unit, causes the yet another storage unit to;

determine whether the yet another storage unit is capable of processing the proxy read request; and

when the yet another storage unit is capable of processing the proxy read request, process the proxy read request.

16. The computer readable memory device of claim 15, wherein the third, fourth, or fifth memory section further stores operational instructions that, when executed by the particular storage unit, the other storage unit, or the yet another storage units, causes the particular storage unit, the other storage unit, or the yet another storage unit to:

notify a requesting computing device of the proxy read request being processed by the yet another storage unit.