Making consistent reads more efficient in IDA+copy system

• US 10,048,897 B2
• Filed: 11/29/2016
• Issued: 08/14/2018
• Est. Priority Date: 11/30/2015
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Baptist, Andrew D., Dhuse, Greg R., Horan, Scott M., Khadiwala, Ravi V., Leggette, Wesley B., Motwani, Manish, Resch, Jason K., Viraraghavan, Praveen, Volvovski, Ilya, Vossberg, Trevor J., Wozniak, Ethan S.
• Primary Examiner(s): Tabone, Jr., John J
• Application Number:
  US15/363,813
• Publication Number:
  US 20170153944A1
• Time in Patent Office: 623 Days
• Field of Search: 714764, 714702, 714718, 714751, 714752, 714763, 714769, 714770, 714773, 714799, 714 61, 714 62, 714 622, 714 624, 714 42, 711111, 711114, 711170, 709231, 707822
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/108 Parity data distribution in semiconductor storages, e.g. in SSD
• CPC Class Codes: G06F 11/1088 Reconstruction on already foreseen single or plurality of spare disks
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G06F 11/1402 Saving, restoring, recovering or retrying
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 12/0891 using clearing, invalidating or resetting means
• CPC Class Codes: G06F 15/17331 Distributed shared memory [DSM], e.g. remote direct memory access [RDMA]
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: G06F 2211/1007 Addressing errors, i.e. silent errors in RAID, e.g. sector slipping and addressing errors
• CPC Class Codes: G06F 2212/1024 Latency reduction
• CPC Class Codes: G06F 2212/154 Networked environment
• CPC Class Codes: G06F 2212/263 Network storage, e.g. SAN or NAS
• CPC Class Codes: G06F 2212/403 Error protection encoding, e.g. using parity or ECC codes
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0629 Configuration or reconfiguration of 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 3/0665 : 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: G06F 9/4881 : Scheduling strategies for dispatcher, e.g. round robin, multi-level priority queues
• CPC Class Codes: G06F 9/5083 : Techniques for rebalancing the load in a distributed system
• CPC Class Codes: H03M 13/1105 : Decoding
• 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: H03M 13/616 : Matrix operations, especially for generator matrices or check matrices, e.g. column or row permutations
• CPC Class Codes: H03M 13/6502 : Reduction of hardware complexity or efficient processing
• CPC Class Codes: H04L 2101/604 : Address structures or formats
• CPC Class Codes: H04L 61/457 : containing identifiers of data entities on a computer, e.g. file names
• CPC Class Codes: H04L 63/101 : Access control lists [ACL]
• 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 computing device includes an interface configured to interface and communicate with a dispersed storage network (DSN), a memory that stores operational instructions, and a processing module operably coupled to the interface and memory such that the processing module, when operable within the computing device based on the operational instructions, is configured to perform various operations. The computing device receives a data access request for a data object and determines a first revision number of a corresponding set of EDSs stored among first SU(s) and a second revision number of a corresponding trimmed copy of the set of EDSs stored among second SU(s). When the second revision number compares favorably to the first revision number, the computing device issues the data access request to the first SU(s) and/or the second SU(s) and issues the data access request for the data object to only the first SU(s) when it doesn'"'"'t.

Claims

1. A computing device comprising:

an interface configured to interface and communicate with a dispersed storage network (DSN);

memory that stores operational instructions; and

a processing module operably coupled to the interface and to the memory, wherein the processing module, when operable within the computing device based on the operational instructions, is configured to;

receive a data access request for a data object, wherein the data object is segmented into a plurality of data segments, wherein a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce a set of encoded data slices (EDSs), wherein a decode threshold number of EDSs are needed to recover the data segment, wherein a read threshold number of EDSs provides for reconstruction of the data segment, wherein the set of EDSs are distributedly stored among a first plurality of storage units (SUs), and wherein a trimmed copy of the set of EDSs that includes fewer than all EDSs of the set of EDSs and includes at least the decode threshold number of EDSs are distributedly stored among a second plurality of SUs;

determine a first revision number that corresponds to the set of EDSs that are distributedly stored among the first plurality of SUs;

determine a second revision number that corresponds to the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs;

when the second revision number compares favorably to the first revision number, issue the data access request for the data object to at least one of the set of EDSs that are distributedly stored among the first plurality of SUs or the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs for at least one of the decode threshold number of EDSs or the read threshold number of EDSs; and

when the second revision number compares unfavorably to the first revision number, issue the data access request for the data object to only the set of EDSs that are distributedly stored among the first plurality of SUs for the at least one of the decode threshold number of EDSs or the read threshold number of EDSs.

2. The computing device of claim 1, wherein the processing module, when operable within the computing device based on the operational instructions, is further configured to:

when the second revision number compares favorably to the first revision number, issue the data access request for the data object to both the set of EDSs that are distributedly stored among the first plurality of SUs and the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs for at least one of the decode threshold number of EDSs or the read threshold number of EDSs.

3. The computing device of claim 1, wherein the processing module, when operable within the computing device based on the operational instructions, is further configured to:

when the second revision number compares unfavorably to the first revision number, issue a rebuild request to generate another trimmed copy of the set of EDSs having the first revision number based on the set of EDSs having the first revision number to be distributedly stored among the second plurality of SUs.

4. The computing device of claim 1, wherein the processing module, when operable within the computing device based on the operational instructions, is further configured to:

when the second revision number compares unfavorably to the first revision number, issue a copy request from another trimmed copy of the set of EDSs having the first revision number that are distributedly stored among a third plurality of SUs to be copied to and distributedly stored among the second plurality of SUs in place of the trimmed copy of the set of EDSs having the second revision number.

5. The computing device of claim 1, wherein the processing module, when operable within the computing device based on the operational instructions, is further configured to:

issue at least one of a first read request or a first write request to the first plurality of SUs to determine the first revision number that corresponds to the set of EDSs that are distributedly stored among the first plurality of SUs; and

issue at least one of a second read request or a second write request to the second plurality of SUs to determine the second revision number that corresponds to the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs.

6. The computing device of claim 1, wherein the processing module, when operable within the computing device based on the operational instructions, is further configured to:

determine a third revision number that corresponds to another trimmed copy of the set of EDSs that are distributedly stored among a third plurality of SUs, wherein the another trimmed copy of the set of EDSs also includes fewer than all EDSs of the set of EDSs and also includes at least the decode threshold number of EDSs;

when both the second revision number and the third revision number compare favorably to the first revision number, issue the data access request for the data object to the set of EDSs that are distributedly stored among the first plurality of SUs, the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs, and the another trimmed copy of the set of EDSs that are distributedly stored among the third plurality of SUs for at least one of the decode threshold number of EDSs or the read threshold number of EDSs;

when both the second revision number compares unfavorably to the first revision number and the third revision number compares favorably to the first revision number, issue the data access request for the data object to only the set of EDSs that are distributedly stored among the first plurality of SUs and the another trimmed copy of the set of EDSs that are distributedly stored among the third plurality of SUs for the at least one of the decode threshold number of EDSs or the read threshold number of EDSs; and

when both the second revision number and the third revision number compares unfavorably to the first revision number, issue the data access request for the data object to only the set of EDSs that are distributedly stored among the first plurality of SUs for the at least one of the decode threshold number of EDSs or the read threshold number of EDSs.

7. The computing device of claim 1, wherein another trimmed copy of the set of EDSs are distributedly stored among a third plurality of SUs, wherein the data segment of the plurality of data segments is dispersed error encoded in accordance with other dispersed error encoding parameters to produce another set of EDSs, wherein another decode threshold number of the another set of EDSs are needed to recover the data segment, wherein another read threshold number of the another set of EDSs provides for reconstruction of the data segment.

8. The computing device of claim 1, wherein the computing device is located at a first premises that is remotely located from at least one SU of the first plurality of SUs or the second plurality of SUs within the DSN.

9. The computing device of claim 1 further comprising:

a SU of the first plurality of SUs or the second plurality of SUs within the DSN, a wireless smart phone, a laptop, a tablet, a personal computers (PC), a work station, or a video game device.

10. The computing device of claim 1, wherein the DSN includes at least one of a wireless communication system, a wire lined communication system, a non-public intranet system, a public internet system, a local area network (LAN), or a wide area network (WAN).

11. A computing device comprising:

an interface configured to interface and communicate with a dispersed storage network (DSN);

memory that stores operational instructions; and

a processing module operably coupled to the interface and to the memory, wherein the processing module, when operable within the computing device based on the operational instructions, is configured to;

receive a data access request for a data object, wherein the data object is segmented into a plurality of data segments, wherein a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce a set of encoded data slices (EDSs), wherein a decode threshold number of EDSs are needed to recover the data segment, wherein a read threshold number of EDSs provides for reconstruction of the data segment, wherein the set of EDSs are distributedly stored among a first plurality of storage units (SUs), and wherein a trimmed copy of the set of EDSs that includes fewer than all EDSs of the set of EDSs and includes at least the decode threshold number of EDSs are distributedly stored among a second plurality of SUs;

determine a first revision number that corresponds to the set of EDSs that are distributedly stored among the first plurality of SUs;

determine a second revision number that corresponds to the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs;

when the second revision number compares favorably to the first revision number, issue the data access request for the data object to at least one of the set of EDSs that are distributedly stored among the first plurality of SUs or the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs for at least one of the decode threshold number of EDSs or the read threshold number of EDSs; and

when the second revision number compares unfavorably to the first revision number, issue the data access request for the data object to only the set of EDSs that are distributedly stored among the first plurality of SUs for the at least one of the decode threshold number of EDSs or the read threshold number of EDSs; and

at least one of;

issue a rebuild request to generate another trimmed copy of the set of EDSs having the first revision number based on the set of EDSs having the first revision number to be distributedly stored among the second plurality of SUs;

or

issue a copy request from another trimmed copy of the set of EDSs having the first revision number that are distributedly stored among a third plurality of SUs to be copied to and distributedly stored among the second plurality of SUs in place of the trimmed copy of the set of EDSs having the second revision number.

12. The computing device of claim 11, wherein the processing module, when operable within the computing device based on the operational instructions, is further configured to:

when the second revision number compares favorably to the first revision number, issue the data access request for the data object to both the set of EDSs that are distributedly stored among the first plurality of SUs and the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs for at least one of the decode threshold number of EDSs or the read threshold number of EDSs.

13. The computing device of claim 11, wherein the processing module, when operable within the computing device based on the operational instructions, is further configured to:

issue at least one of a first read request or a first write request to the first plurality of SUs to determine the first revision number that corresponds to the set of EDSs that are distributedly stored among the first plurality of SUs; and

issue at least one of a second read request or a second write request to the second plurality of SUs to determine the second revision number that corresponds to the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs.

14. The computing device of claim 11, wherein the processing module, when operable within the computing device based on the operational instructions, is further configured to:

determine a third revision number that corresponds to another trimmed copy of the set of EDSs that are distributedly stored among the third plurality of SUs, wherein the another trimmed copy of the set of EDSs also includes fewer than all EDSs of the set of EDSs and also includes at least the decode threshold number of EDSs;

when both the second revision number and the third revision number compare favorably to the first revision number, issue the data access request for the data object to the set of EDSs that are distributedly stored among the first plurality of SUs, the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs, and the another trimmed copy of the set of EDSs that are distributedly stored among the third plurality of SUs for at least one of the decode threshold number of EDSs or the read threshold number of EDSs;

when both the second revision number compares unfavorably to the first revision number and the third revision number compares favorably to the first revision number, issue the data access request for the data object to only the set of EDSs that are distributedly stored among the first plurality of SUs and the another trimmed copy of the set of EDSs that are distributedly stored among the third plurality of SUs for the at least one of the decode threshold number of EDSs or the read threshold number of EDSs; and

when both the second revision number and the third revision number compares unfavorably to the first revision number, issue the data access request for the data object to only the set of EDSs that are distributedly stored among the first plurality of SUs for the at least one of the decode threshold number of EDSs or the read threshold number of EDSs.

15. The computing device of claim 11, wherein another trimmed copy of the set of EDSs are distributedly stored among a third plurality of SUs, wherein the data segment of the plurality of data segments is dispersed error encoded in accordance with other dispersed error encoding parameters to produce another set of EDSs, wherein another decode threshold number of the another set of EDSs are needed to recover the data segment, wherein another read threshold number of the another set of EDSs provides for reconstruction of the data segment.

16. The computing device of claim 11 further comprising:

a SU of the first plurality of SUs or the second plurality of SUs within the DSN, a wireless smart phone, a laptop, a tablet, a personal computers (PC), a work station, or a video game device.

17. The computing device of claim 11, wherein the DSN includes at least one of a wireless communication system, a wire lined communication system, a non-public intranet system, a public internet system, a local area network (LAN), or a wide area network (WAN).

18. A method for execution by a computing device, the method comprising:

receiving, via an interface configured to interface and communicate with a dispersed storage network (DSN), a data access request for a data object, wherein the data object is segmented into a plurality of data segments, wherein a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce a set of encoded data slices (EDSs), wherein a decode threshold number of EDSs are needed to recover the data segment, wherein a read threshold number of EDSs provides for reconstruction of the data segment, wherein the set of EDSs are distributedly stored among a first plurality of storage units (SUs), and wherein a trimmed copy of the set of EDSs that includes fewer than all EDSs of the set of EDSs and includes at least the decode threshold number of EDSs are distributedly stored among a second plurality of SUs;

determining a first revision number that corresponds to the set of EDSs that are distributedly stored among the first plurality of SUs;

determining a second revision number that corresponds to the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs;

when the second revision number compares favorably to the first revision number, issuing the data access request for the data object via the interface to at least one of the set of EDSs that are distributedly stored among the first plurality of SUs or the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs for at least one of the decode threshold number of EDSs or the read threshold number of EDSs; and

when the second revision number compares unfavorably to the first revision number, issuing the data access request for the data object via the interface to only the set of EDSs that are distributedly stored among the first plurality of SUs for the at least one of the decode threshold number of EDSs or the read threshold number of EDSs.

19. The method of claim 18 further comprising:

when the second revision number compares favorably to the first revision number, issuing the data access request for the data object via the interface to both the set of EDSs that are distributedly stored among the first plurality of SUs and the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs for at least one of the decode threshold number of EDSs or the read threshold number of EDSs.

20. The method of claim 18 further comprising:

when the second revision number compares unfavorably to the first revision number, issuing via the interface a rebuild request to generate another trimmed copy of the set of EDSs having the first revision number based on the set of EDSs having the first revision number to be distributedly stored among the second plurality of SUs.

21. The method of claim 18 further comprising:

when the second revision number compares unfavorably to the first revision number, issuing via the interface a copy request from another trimmed copy of the set of EDSs having the first revision number that are distributedly stored among a third plurality of SUs to be copied to and distributedly stored among the second plurality of SUs in place of the trimmed copy of the set of EDSs having the second revision number.

22. The method of claim 18 further comprising:

issuing via the interface at least one of a first read request or a first write request to the first plurality of SUs to determine the first revision number that corresponds to the set of EDSs that are distributedly stored among the first plurality of SUs; and

issuing via the interface at least one of a second read request or a second write request to the second plurality of SUs to determine the second revision number that corresponds to the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs.

23. The method of claim 18 further comprising:

determining a third revision number that corresponds to another trimmed copy of the set of EDSs that are distributedly stored among a third plurality of SUs, wherein the another trimmed copy of the set of EDSs also includes fewer than all EDSs of the set of EDSs and also includes at least the decode threshold number of EDSs;

when both the second revision number and the third revision number compare favorably to the first revision number, issuing via the interface the data access request for the data object to the set of EDSs that are distributedly stored among the first plurality of SUs, the trimmed copy of the set of EDSs that are distributedly stored among the second plurality of SUs, and the another trimmed copy of the set of EDSs that are distributedly stored among the third plurality of SUs for at least one of the decode threshold number of EDSs or the read threshold number of EDSs;

when both the second revision number compares unfavorably to the first revision number and the third revision number compares favorably to the first revision number, issuing via the interface the data access request for the data object to only the set of EDSs that are distributedly stored among the first plurality of SUs and the another trimmed copy of the set of EDSs that are distributedly stored among the third plurality of SUs for the at least one of the decode threshold number of EDSs or the read threshold number of EDSs; and

when both the second revision number and the third revision number compares unfavorably to the first revision number, issuing via the interface the data access request for the data object to only the set of EDSs that are distributedly stored among the first plurality of SUs for the at least one of the decode threshold number of EDSs or the read threshold number of EDSs.

24. The method of claim 18, wherein the computing device is a SU of the first plurality of SUs or the second plurality of SUs within the DSN, a wireless smart phone, a laptop, a tablet, a personal computers (PC), a work station, or a video game device.

25. The method of claim 18, wherein the DSN includes at least one of a wireless communication system, a wire lined communication system, a non-public intranet system, a public internet system, a local area network (LAN), or a wide area network (WAN).