Migration of encoded data slices in a dispersed storage network

• US 10,037,140 B2
• Filed: 08/05/2014
• Issued: 07/31/2018
• Est. Priority Date: 10/03/2013
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Baptist, Andrew, Kaczmarek, Joseph Martin
• Primary Examiner(s): Yi, David X
• Assistant Examiner(s): PUCHE, TAHILBA O
• Application Number:
  US14/452,483
• Publication Number:
  US 20150100727A1
• Time in Patent Office: 1,456 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 12/1458 by checking the subject access rights
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 16/182 Distributed file systems
• CPC Class Codes: G06F 21/31 User authentication
• CPC Class Codes: G06F 21/6272 by registering files or documents with a third party
• CPC Class Codes: G06F 2211/1028 Distributed, i.e. distributed RAID systems with parity
• CPC Class Codes: G06F 2212/1052 Security improvement
• CPC Class Codes: G06F 2212/154 Networked environment
• CPC Class Codes: G06F 2221/2149 Restricted operating environment
• 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 3/0622 in relation to access
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration
• CPC Class Codes: G06F 3/0637 Permissions
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0655 Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices
• 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 3/0682 : Tape device
• 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: H04L 67/1001 : for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1095 : Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• 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 67/145 : avoiding end of session, e.g. keep-alive, heartbeats, resumption message or wake-up for inactive or interrupted session

Abstract

A method includes a processing module of a storage unit of a dispersed storage network (DSN) monitoring input/output (IO) rates of a plurality of disk drives, where access requests for encoded data slices occur at varying rates. The method continues with the processing module determining that the IO rate of a disk drive is exceeding a desired maximum IO rate and identifying a pending access request for an encoded data slice stored in the disk drive. The method continues with the processing module evaluating disk drive processing rates of other storage units that are storing other encoded data slices of a set of encoded data slices that includes the encoded data slice to determine whether the encoded data slice is needed to satisfy the pending access request. When the encoded data slice is needed, the method continues with the processing module migrating the encoded data slice to another disk drive.

Claims

1. A method for execution by one or more processing modules of a storage unit of a dispersed storage network (DSN), the method comprises:

monitoring input/output (IO) rates of a plurality of disk drives, wherein the storage unit stores a plurality of encoded data slices from a plurality of sets of encoded data slices in at least some of the plurality of disk drives, and wherein access requests for encoded data slices of the plurality of encoded data slices occur at varying rates;

determining that the IO rate of a first disk drive of the plurality of disk drives is exceeding a desired maximum IO rate;

identifying a pending access request for a first encoded data slice of the plurality of encoded data slices stored in the first disk drive, wherein the first encoded data slice is of a first set of encoded data slices of the plurality of sets of encoded data slices, and wherein a decode threshold number of encoded data slices of the first set of encoded data slices is needed to reconstruct a data segment;

evaluating disk drive processing rates of other storage units that are storing other encoded data slices of the first set of encoded data slices to determine whether the first encoded data slice is needed to satisfy the pending access request, wherein the evaluating the disk drive processing rates of the other storage units by;

receiving, from each of the other storage units, disk drive processing rates for each of a plurality of other disk drives;

identifying, for each of the other storage units, the disk drive processing rate of another disk drive of the plurality of other disk drives storing one of the other encoded data slices;

determining whether the decode threshold number of the plurality of other disk drives have an IO rate below the desired maximum IO rate;

when less than the decode threshold number of the plurality of other disk drives have an IO rate below the desired maximum IO rate, indicating that the first encoded data slice is needed; and

when the decode threshold number of the plurality of other disk drives have an IO rate below the desired maximum IO rate, indicating that the first encoded data slice is not needed; and

when the first encoded data slice is needed, migrating the first encoded data slice to another disk drive of the plurality of disk drives.

2. The method of claim 1, wherein the identifying the pending access request comprises one or more of:

analyzing historical access request information regarding similar access requests to the pending access request; and

determining a likelihood of future similar access requests to the pending access request.

3. The method of claim 1, wherein the identifying the pending access request comprises:

determining that multiple similar access requests to the pending access request are pending in an access request queue.

4. The method of claim 1, wherein the evaluating the disk drive processing rates of the other storage units comprises:

sending requests for the disk drive processing rates to the other storage units, wherein one of the requests includes identity of the first encoded data slice or identity of one of the other encoded data slices.

5. The method of claim 1 further comprises:

when the first encoded data slice is not needed, deleting the pending access request for the first encoded data slice.

6. A computer readable non-transitory storage medium comprises:

at least one memory section that stores operational instructions that, when executed by one or more processing modules of a storage unit of a dispersed storage network (DSN), causes the storage unit to;

monitor input/output (IO) rates of a plurality of disk drives, wherein the storage unit stores a plurality of encoded data slices from a plurality of sets of encoded data slices in at least some of the plurality of disk drives, and wherein access requests for encoded data slices of the plurality of encoded data slices occur at varying rates;

determine that the IO rate of a first disk drive of the plurality of disk drives is exceeding a desired maximum IO rate;

identify a pending access request for a first encoded data slice of the plurality of data slices stored in the first disk drive, wherein the first encoded data slice is of a first set of encoded data slices of the plurality of sets of encoded data slices, and wherein a decode threshold number of encoded data slices of the first set of encoded data slices is needed to reconstruct a data segment;

evaluate disk drive processing rates of other storage units that are storing other encoded data slices of the first set of encoded data slices to determine whether the first encoded data slice is needed to satisfy the pending access request, wherein the disk drive processing rates of the other storage units are evaluated by;

receiving, from each of the other storage units, disk drive processing rates for each of a plurality of other disk drives;

identifying, for each of the other storage units, the disk drive processing rate of another disk drive of the plurality of other disk drives storing one of the other encoded data slices;

determining whether the decode threshold number of the plurality of other disk drives have an IO rate below the desired maximum IO rate;

when less than the decode threshold number of the plurality of other disk drives have an IO rate below the desired maximum IO rate, indicating that the first encoded data slice is needed; and

when the decode threshold number of the plurality of other disk drives have an IO rate below the desired maximum IO rate, indicating that the first encoded data slice is not needed; and

when the first encoded data slice is needed, migrate the first encoded data slice to another disk drive of the plurality of disk drives.

7. The computer readable non-transitory storage medium of claim 6, wherein the one or more processing modules functions to execute the operational instructions stored by the at least one memory section to cause the one or more computing devices of the DSN to identify the pending access request by one or more of:

analyzing historical access request information regarding similar access requests to the pending access request; and

determining a likelihood of future similar access requests to the pending access request.

8. The computer readable non-transitory storage medium of claim 6, wherein the one or more processing modules functions to execute the operational instructions stored by the at least one memory section to cause the one or more computing devices of the DSN to identify the pending access request by:

determining that multiple similar access requests to the pending access request are pending in an access request queue.

9. The computer readable non-transitory storage medium of claim 6, wherein the one or more processing modules functions to execute the operational instructions stored by the at least one memory section to cause the one or more computing devices of the DSN to evaluate the disk drive processing rates of the other storage units by:

sending requests for the disk drive processing rates to the other storage units, wherein one of the requests includes identity of the first encoded data slice or identity of one of the other encoded data slices.

10. The computer readable non-transitory storage medium of claim 6 further comprises:

the at least one memory section stores further operational instructions that, when executed by the one or more processing modules, causes the one or more computing devices of the DSN to;

when the first encoded data slice is not needed, delete the pending access request for the first encoded data slice.

11. A storage unit of a dispersed storage network (DSN), the storage unit comprises:

an interface;

a memory; and

a processing module operably coupled to the interface and the memory, wherein the processing module functions to;

monitor input/output (IO) rates of a plurality of disk drives, wherein the storage unit stores, in the memory, a plurality of encoded data slices from a plurality of sets of encoded data slices in at least some of the plurality of disk drives, and wherein access requests for encoded data slices of the plurality of encoded data slices occur at varying rates;

determine that the IO rate of a first disk drive of the plurality of disk drives is exceeding a desired maximum IO rate;

identify a pending access request for a first encoded data slice of the plurality of data slices stored in the first disk drive, wherein the first encoded data slice is of a first set of encoded data slices of the plurality of sets of encoded data slices and wherein a decode threshold number of encoded data slices of the first set of encoded data slices is needed to reconstruct a data segment;

evaluate disk drive processing rates of other storage units that are storing other encoded data slices of the first set of encoded data slices to determine whether the first encoded data slice is needed to satisfy the pending access request, wherein the disk drive processing rates of the other storage units are evaluated by;

receiving, from each of the other storage units, disk drive processing rates for each of a plurality of other disk drives;

identifying, for each of the other storage units, the disk drive processing rate of another disk drive of the plurality of other disk drives storing one of the other encoded data slices;

determining whether the decode threshold number of the plurality of other disk drives have an IO rate below the desired maximum IO rate;

when less than the decode threshold number of the plurality of other disk drives have an IO rate below the desired maximum IO rate, indicating that the first encoded data slice is needed; and

when the decode threshold number of the plurality of other disk drives have an IO rate below the desired maximum IO rate, indicating that the first encoded data slice is not needed; and

when the first encoded data slice is needed, migrate the first encoded data slice to another disk drive of the plurality of disk drives.

12. The storage unit of claim 11, wherein the processing module functions to identify the pending access request by one or more of:

analyzing historical access request information regarding similar access requests to the pending access request; and

determining a likelihood of future similar access requests to the pending access request.

13. The storage unit of claim 11, wherein the processing module functions to identify the pending access request by:

determining that multiple similar access requests to the pending access request are pending in an access request queue.

14. The storage unit of claim 11, wherein the processing module functions to evaluate the disk drive processing rates of the other storage units by:

sending, via the interface, requests for the disk drive processing rates to the other storage units, wherein one of the requests includes identity of the first encoded data slice or identity of one of the other encoded data slices.

15. The storage unit of claim 11, wherein the processing module further functions to:

when the first encoded data slice is not needed, delete, from a pending request memory, the pending access request for the first encoded data slice.