Updating a set of memory devices in a dispersed storage network

• US 9,122,596 B2
• Filed: 04/21/2014
• Issued: 09/01/2015
• Est. Priority Date: 11/01/2010
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Cleversafe Incorporated (International Business Machines Corporation)
• Inventors: Grube, Gary W., Markison, Timothy W.
• Primary Examiner(s): BUTLER, SARAI E
• Application Number:
  US14/257,398
• Publication Number:
  US 20140229775A1
• Time in Patent Office: 498 Days
• Field of Search: 714/42, 714/25
• US Class Current: 1/1
• CPC Class Codes: G06F 11/0727 in a storage system, e.g. in a DASD or network based storage system drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; 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], H04L67/1097
• CPC Class Codes: G06F 16/972 Access to data in other repository systems, e.g. legacy data or dynamic Web page generation

Abstract

A method begins by tracking age related failure levels of memory devices within the storage unit. The method continues by maintaining a data location table that maps a range of DSN addresses allocated to the storage unit to the memory devices and further records storing of encoded data slices having specific DSN addresses within the memory devices. The method continues, when the age related failure level for a memory device compares unfavorably to a first failure level threshold, by determining to reassign a portion of DSN addresses assigned to the memory device. The method continues by identifying a second memory device having a corresponding age related soft failure level comparing favorable to the first failure level threshold. The method continues by reassigning the portion of the DSN addresses from the memory device to the second memory device and updating the data location table.

Claims

1. A method for execution by a storage unit of a distributed storage network (DSN), the method comprises:

tracking age related failure levels of a plurality of memory devices within the storage unit in a memory assignment table;

maintaining a data location table that maps a range of DSN addresses allocated to the storage unit to the plurality of memory devices and further records storing of encoded data slices having specific DSN addresses within corresponding ones of the plurality of memory devices;

when the age related failure level for a memory device of the plurality of memory devices compares unfavorably to a first failure level threshold;

determining to reassign a portion of DSN addresses assigned to the memory device;

identifying a second memory device of the plurality of memory devices having a corresponding age related soft failure level comparing favorable to the first failure level threshold;

reassigning the portion of the DSN addresses from the memory device to the second memory device; and

updating the data location table in accordance with the reassigning the portion of the DSN addresses.

2. The method of claim 1 further comprises:

updating the memory assignment table by adjusting an age related failure field for the memory device to reflect the unfavorable comparison of the age related failure level to the first failure level threshold, wherein the memory assignment table includes a plurality of entries, and wherein an entry of the plurality of entries includes a memory identifier field, an allocation status field, and an age related failure level field.

3. The method of claim 1 further comprises:

identifying encoded data slices having DSN addresses in the portion of the DSN addresses; and

transferring storage of the encoded data slices having the DSN addresses in the portion of the DSN addresses from the memory device to the second memory device.

4. The method of claim 1 further comprises:

identifying encoded data slices having DSN addresses in the portion of the DSN addresses; and

determining whether an encoded data slice of the encoded data slices having the DSN address in the portion of the DSN addresses requires rebuilding; and

when the encoded data slice of the encoded data slices having the DSN address in the portion of the DSN addresses requires rebuilding, flagging the encoded data slice for rebuilding.

5. The method of claim 1, wherein the tracking the age related failure levels comprises:

for each of the plurality of memory devices, determining error characteristics, wherein the error characteristics include one or more of real-time stored errors, historical storage errors, retrieval errors, latency performance outside of a specification, and a performance factor out of specification.

6. The method of claim 1 further comprises:

when the age related failure level for the memory device compares unfavorably to a second failure level threshold;

determining whether to decommission and replace the memory device, decommission the memory device and utilize a third memory device, reassigning a second portion of the DSN addresses from the memory device to the second memory device;

when the determination is to decommission and replace the memory device;

decommissioning the memory device; and

when a replacement memory device is commissioned, storing encoded data slices that were stored on the memory device on the replacement memory device.

7. The method of claim 6, wherein the storing the encoded data slices on the replacement memory device further comprises one of:

caching the encoding data slices and, when the replacement memory device is commissioned, copying the cached encoded data slices onto the replacement memory device; and

flagging the encoded data slices for rebuilding and, when the replacement memory device is commissioned, storing rebuilt encoded data slices in the replacement memory device.

8. The method of claim 6 further comprises:

when the determination is to decommission and utilize the third memory device;

decommissioning the memory device; and

storing encoded data slices that were stored on the memory device on the third memory device.

9. The method of claim 6 further comprises:

when the determination is to reassign the second portion of the DSN addresses from the memory device to the second memory device;

reassigning the second portion of the DSN addresses from the memory device to the second memory device; and

updating the data location table in accordance with the reassigning the second portion of the DSN addresses.

10. The method of claim 1 further comprises:

analyzing commutative age related failure levels of the plurality of memories; and

when the cumulative age related failure levels compare unfavorably to a cumulative failure threshold level, facilitating decommissioning of the storage unit in light of cumulative age related failure levels of other storage units of the DSN, wherein the storage unit and other storage units store encoded data slices of commonly encoded data segments.

11. A computer readable storage device comprises:

a first memory for storing operational instructions that, when executed by a computing device, causes the computing device to;

track age related failure levels of a plurality of memory devices within the storage unit in a memory assignment table; and

maintain a data location table that maps a range of DSN addresses allocated to the storage unit to the plurality of memory devices and further records storing of encoded data slices having specific DSN addresses within corresponding ones of the plurality of memory devices;

a second memory for storing operational instructions that, when executed by at least one of the computing device and a second computing device, causes the at least one of the computing device and the second computing device to;

when the age related failure level for a memory device of the plurality of memory devices compares unfavorably to a first failure level threshold;

determine to reassign a portion of DSN addresses assigned to the memory device;

identify a second memory device of the plurality of memory devices having a corresponding age related soft failure level comparing favorable to the first failure level threshold;

reassign the portion of the DSN addresses from the memory device to the second memory device; and

update the data location table in accordance with the reassigning the portion of the DSN addresses.

12. The computer readable storage device of claim 11, wherein the first memory further stores operational instructions that, when executed by the computing device, causes the computing device to:

update the memory assignment table by adjusting an age related failure field for the memory device to reflect the unfavorable comparison of the age related failure level to the first failure level threshold, wherein the memory assignment table includes a plurality of entries, and wherein an entry of the plurality of entries includes a memory identifier field, an allocation status field, and an age related failure level field.

13. The computer readable storage device of claim 11, wherein the first memory further stores operational instructions that, when executed by the computing device, causes the computing device to:

identifying encoded data slices having DSN addresses in the portion of the DSN addresses; and

transferring storage of the encoded data slices having the DSN addresses in the portion of the DSN addresses from the memory device to the second memory device.

14. The computer readable storage device of claim 11, wherein the first memory further stores operational instructions that, when executed by the computing device, causes the computing device to:

identifying encoded data slices having DSN addresses in the portion of the DSN addresses; and

determining whether an encoded data slice of the encoded data slices having the DSN address in the portion of the DSN addresses requires rebuilding; and

when the encoded data slice of the encoded data slices having the DSN address in the portion of the DSN addresses requires rebuilding, flagging the encoded data slice for rebuilding.

15. The computer readable storage device of claim 11, wherein the first memory further stores operational instructions that, when executed by the computing device, causes the computing device to track the age related failure levels by:

for each of the plurality of memory devices, determining error characteristics, wherein the error characteristics include one or more of real-time stored errors, historical storage errors, retrieval errors, latency performance outside of a specification, and a performance factor out of specification.

16. The computer readable storage device of claim 11, wherein the second memory further stores operational instructions that, when executed by the at least one of the computing device and the second computing device, causes the at least one of the computing device and the second computing device to:

when the age related failure level for the memory device compares unfavorably to a second failure level threshold;

determine whether to decommission and replace the memory device, decommission the memory device and utilize a third memory device, reassigning a second portion of the DSN addresses from the memory device to the second memory device;

when the determination is to decommission and replace the memory device;

decommission the memory device; and

when a replacement memory device is commissioned, store encoded data slices that were stored on the memory device on the replacement memory device.

17. The computer readable storage device of claim 16, wherein the second memory further stores operational instructions that, when executed by the at least one of the computing device and the second computing device, causes the at least one of the computing device and the second computing device to store the encoded data slices on the replacement memory device by one of:

caching the encoding data slices and, when the replacement memory device is commissioned, copying the cached encoded data slices onto the replacement memory device; and

flagging the encoded data slices for rebuilding and, when the replacement memory device is commissioned, storing rebuilt encoded data slices in the replacement memory device.

18. The computer readable storage device of claim 16, wherein the second memory further stores operational instructions that, when executed by the at least one of the computing device and the second computing device, causes the at least one of the computing device and the second computing device to:

when the determination is to decommission and utilize the third memory device;

decommission the memory device; and

store encoded data slices that were stored on the memory device on the third memory device.

19. The computer readable storage device of claim 16, wherein the second memory further stores operational instructions that, when executed by the at least one of the computing device and the second computing device, causes the at least one of the computing device and the second computing device to:

when the determination is to reassign the second portion of the DSN addresses from the memory device to the second memory device;

reassign the second portion of the DSN addresses from the memory device to the second memory device; and

update the data location table in accordance with the reassigning the second portion of the DSN addresses.

20. The computer readable storage device of claim 11, wherein the second memory further stores operational instructions that, when executed by the at least one of the computing device and the second computing device, causes the at least one of the computing device and the second computing device to:

analyze commutative age related failure levels of the plurality of memories; and

when the cumulative age related failure levels compare unfavorably to a cumulative failure threshold level, facilitate decommissioning of the storage unit in light of cumulative age related failure levels of other storage units of the DSN, wherein the storage unit and other storage units store encoded data slices of commonly encoded data segments.