Memory device utilization in a dispersed storage network

• US 9,026,758 B2
• Filed: 04/29/2011
• Issued: 05/05/2015
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Cleversafe Incorporated (International Business Machines Corporation)
• Inventors: Baptist, Andrew, Motwani, Manish, Leggette, Wesley, Hoffman, Steven Mark, Hendrickson, Dustin M., Kuester, Ryan Joseph, Gladwin, S. Christopher
• Primary Examiner(s): Li, Aimee
• Assistant Examiner(s): Kolb, Michael C
• Application Number:
  US13/097,305
• Publication Number:
  US 20110289283A1
• Time in Patent Office: 1,467 Days
• US Class Current: 711/165
• 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 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: H04L 2209/04 Masking or blinding
• CPC Class Codes: H04L 2209/24 Key scheduling, i.e. generating round keys or sub-keys for block encryption
• CPC Class Codes: H04L 2209/34 Encoding or coding, e.g. Huffman coding or error correction
• 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 9/085 Secret sharing or secret splitting, e.g. threshold schemes
• CPC Class Codes: H04L 9/0863 involving passwords or one-time passwords network architectures or network communication protocols for using one-time keys in a packet data network H04L63/067
• CPC Class Codes: H04L 9/0869 involving random numbers or seeds
• CPC Class Codes: H04L 9/0894 Escrow, recovery or storing of secret information, e.g. secret key escrow or cryptographic key storage
• CPC Class Codes: H04L 9/14 using a plurality of keys or algorithms

Abstract

A method begins by a processing module determining whether a memory device of a dispersed storage (DS) unit is unavailable to produce an unavailable memory device. The method continues with the processing module determining a methodology regarding DS encoded data stored in the unavailable memory device based on one or more dispersed storage network (DSN) conditions to produce a determined methodology when the memory device is unavailable. The method continues with the processing module initiating, in accordance with the determined methodology, a rebuilding function to rebuild the DS encoded data to produce rebuilt DS encoded data when the determined methodology includes a rebuilding component. The method continues with the processing module storing the rebuilt DS encoded data within available memory of the DS unit.

Claims

1. A method for execution by a processing module of a storage unit, the method comprises:

determining whether a memory device of a dispersed storage (DS) unit is unavailable to produce an unavailable memory device, wherein the DS unit is one of a plurality of DS units of a dispersed storage network (DSN), wherein a data object is dispersed storage error encoding into a plurality of sets of encoded data slices, and wherein the DS unit stores an encoded data slice from at least some sets of the plurality of sets of encoded data slices to produce stored encoded data slices;

when the memory device is unavailable and when the memory device is storing one or more of the stored encoded data slices, determining a methodology regarding the one or more encoded data slices based on one or more DSN conditions to produce a determined methodology;

when the determined methodology includes a rebuilding component, initiating, in accordance with the determined methodology, a rebuilding function to rebuild the one or more encoded data slices to produce rebuilt one or more encoded data slices, wherein the rebuilding function includes obtaining a decode threshold number of encoded data slices for the at least some sets of the plurality of sets of encoded data slices from other DS units of the plurality of DS units; and

storing the rebuilt one or more encoded data slices within available memory of the DS unit.

2. The method of claim 1, wherein the one or more DSN conditions comprises at least one of:

decode threshold and pillar width ratio;

number of DS units in vault that are unavailable;

network traffic; and

priority level of the DS encoded data.

3. The method of claim 1 further comprises:

when the determined methodology includes waiting for the memory device to become available, waiting for the memory device to become available; and

when the memory device becomes available, changing status of the memory device from unavailable to available.

4. The method of claim 1 further comprises, when the determined methodology includes the rebuilding component:

establishing a time period based on the one or more DSN conditions; and

when the time period expires, reassigning a slice name range associated with the unavailable memory device to the available memory of the DS unit prior to the storing the rebuilt one or more encoded data slices.

5. The method of claim 4 further comprises:

when the time period expires, initiating the rebuilding function.

6. The method of claim 1 further comprises, when the determined methodology includes the rebuilding component:

determining that the DS unit includes a hot-standby memory device;

when the DS unit includes the hot-standby memory device, determining, in accordance with the determined methodology, whether to use the hot-standby memory device, wherein the available memory of the DS unit includes the hot-standby memory device; and

when the hot-standby memory device is to be used, reassigning a slice name range associated with the unavailable memory device to the hot-standby memory device prior to the storing the rebuilt one or more encoded data slices.

7. The method of claim 1 further comprises:

determining whether to transfer the rebuilt one or more encoded data slices from the available memory of the DS unit to an additional memory of the DS unit;

when the rebuilt one or more encoded data slices is to be transferred from the available memory of the DS unit to the additional memory, reassigning a slice name range associated with the available memory of the DS unit to the additional memory; and

transferring the rebuilt one or more encoded data slices from the available memory of the DS unit to the additional memory.

8. The method of claim 1, wherein the storing the rebuilt one or more encoded data slices further comprises:

reassigning a slice name range of the unavailable memory device to the available memory of the DS unit, wherein the reassigning the slice name range includes at least one of;

updating the slice name range in a memory device table from the unavailable memory device to the available memory of the DS unit;

when the available memory of the DS unit includes a plurality of memory devices;

partitioning the slice name range into a plurality of slice name range partitions; and

assigning one of the plurality of slice name range partitions to one of the plurality of memory devices; and

updating a status indicator of the unavailable memory.

9. The method of claim 1, wherein the initiating, in accordance with the determined methodology, the rebuilding function comprises at least one of:

executing the rebuilding function to rebuild the one or more encoded data slices; and

requesting execution of the rebuilding function to rebuild the one or more encoded data slices.

10. A dispersed storage (DS) unit comprises:

an interface;

a memory; and

a processing module operable to;

determine whether a memory device of the memory is unavailable to produce an unavailable memory device, wherein the DS unit is one of a plurality of DS units of a dispersed storage network (DSN), wherein a data object is dispersed storage error encoding into a plurality of sets of encoded data slices, and wherein the DS unit stores an encoded data slice from at least some sets of the plurality of sets of encoded data slices to produce stored encoded data slices;

when the memory device is unavailable and when the memory device is storing one or more of the stored encoded data slices, determine a methodology regarding the one or more encoded data slices based on one or more DSN conditions to produce a determined methodology;

when the determined methodology includes a rebuilding component, initiate, in accordance with the determined methodology, a rebuilding function to rebuild the one or more encoded data slices to produce rebuilt one or more encoded data slices, wherein the rebuilding function includes obtaining a decode threshold number of encoded data slices for the at least some sets of the plurality of sets of encoded data slices from other DS units of the plurality of DS units; and

store the rebuilt one or more encoded data slices within available memory of the memory.

11. The DS unit of claim 10, wherein the one or more DSN conditions comprises at least one of:

decode threshold and pillar width ratio;

number of DS units in vault that are unavailable;

network traffic; and

priority level of the DS encoded data.

12. The DS unit of claim 10, wherein the processing module further functions to:

when the determined methodology includes waiting for the memory device to become available, wait for the memory device to become available; and

when the memory device becomes available, change status of the memory device from unavailable to available.

13. The DS unit of claim 10, when the determined methodology includes the rebuilding component, the processing module further functions to:

establish a time period based on the one or more DSN conditions; and

when the time period expires, reassign a slice name range associated with the unavailable memory device to the available memory of the memory prior to the storing the rebuilt one or more encoded data slices.

14. The DS unit of claim 13, wherein the processing module further functions to:

when the time period expires, initiate the rebuilding function.

15. The DS unit of claim 10, when the determined methodology includes the rebuilding component, the processing module further functions to:

determine that the memory includes a hot-standby memory device;

when the memory includes the hot-standby memory device, determine, in accordance with the determined methodology, whether to use the hot-standby memory device, wherein the available memory of the memory includes the hot-standby memory device; and

when the hot-standby memory device is to be used, reassign a slice name range associated with the unavailable memory device to the hot-standby memory device prior to the storing the rebuilt one or more encoded data slices.

16. The DS unit of claim 10, wherein the processing module further functions to:

determine whether to transfer the rebuilt one or more encoded data slices from the available memory of the memory to an additional memory of the memory;

when the rebuilt one or more encoded data slices is to be transferred from the available memory of the memory to the additional memory, reassign a slice name range associated with the available memory of the memory to the additional memory; and

transferring the rebuilt one or more encoded data slices from the available memory of the memory to the additional memory.

17. The DS unit of claim 10, wherein the processing module further functions to store the rebuilt DS encoded data by:

reassigning a slice name range of the unavailable memory device to the available memory of the memory, wherein the reassigning the slice name range includes at least one of;

updating the slice name range in a memory device table from the unavailable memory device to the available memory of the memory;

when the available memory of the memory includes a plurality of memory devices;

partitioning the slice name range into a plurality of slice name range partitions; and

assigning one of the plurality of slice name range partitions to one of the plurality of memory devices; and

updating a status indicator of the unavailable memory.

18. The DS unit of claim 10, wherein processing module further functions to initiate, in accordance with the determined methodology, the rebuilding function by at least one of:

executing the rebuilding function to rebuild the one or more encoded data slices; and

requesting, via the interface, execution of the rebuilding function to rebuild the one or more encoded data slices.