Wear leveling in storage devices

Patent metadata

Field	Value
Publication number	US-9842059-B2
Application number	US-201615098668-A
Country	US
Kind code	B2
Filing date	Apr 14, 2016
Priority date	Apr 14, 2016
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

A system may include a plurality of memory cells and a processor. The plurality of memory cells may include a plurality of physical locations at which data is stored. The processor may be configured to determine whether to swap physical locations of data stored at logical block addresses in the first logical block address collection and physical locations of data stored at logical block addresses in the second logical block address collection. The processor may be further configured to, in response to determining to swap the physical locations of the data, swap the physical locations of the data stored at the logical block addresses in the first logical block address collection and the physical locations of the data stored at the logical block addresses in the second logical block address collection.

First claim

What is claimed is:

1. A system comprising: a plurality of memory devices comprising a plurality of physical locations at which data is stored; a processor configured to: determine, based on a value of a first transient write counter associated with a first logical block address collection and a value of a second transient write counter associated with a second logical block address collection, whether to swap physical locations of data stored at logical block addresses in the first logical block address collection and physical locations of data stored at logical block addresses in the second logical block address collection, wherein: the value of the first transient write counter equals a number of times data has been written to the first logical block address collection since a prior data swap involving the first logical block address collection, and the value of the second transient write counter equals a number of times data has been written to the second logical block address collection since a prior data swap involving the second logical block address collection; and in response to determining to swap the physical locations of the data stored at logical block addresses in the first logical block address collection and the physical locations of the data stored at logical block addresses in the second logical block address collection: swap the physical locations of the data stored at the logical block addresses in the first logical block address collection and the physical locations of the data stored at the logical block addresses in the second logical block address collection; and
wherein the processor is configured to determine whether to swap physical locations of the data stored at logical block addresses in the first logical block address collection and physical locations of the data stored at logical block addresses in the second logical block address collection by at least: summing the value of the first transient write counter with a value of a first permanent write counter associated with the first logical block address collection to determine a first total write value indicating a total number of writes to the first logical block address collection, wherein the value of the first permanent write counter equals the number of times data was written to the first logical block address collection before a prior data swap involving the first logical block address collection; summing the value of the second transient write counter with a value of a second permanent write counter associated with the second logical block address collection to determine a second total write value indicating a total number of writes to the second logical block address collection, wherein the value of the second permanent write counter equals the number of times data was written to the second logical block address collection before a prior data swap involving the second logical block address collection; and determining whether the first total write value is greater than a predetermined number multiplied by the second total write value.

2. The system of claim 1 , wherein the processor is configured to determine whether to swap physical locations of the data stored at logical block addresses in the first logical block address collection and physical locations of the data stored at logical block addresses in the second logical block address collection by at least:
determine whether the value of the first transient write counter is greater than a predetermined number multiplied by the value of the second transient write counter.

3. The system of claim 1 , wherein the processor is further configured to:
in response to determining that a sum of the value of the first transient write counter and a value of a first permanent write counter associated with the first logical block address collection exceeds a threshold block collection write count, rearrange, based on an offset value associated with the first logical block address collection, physical locations of data stored at logical addresses associated with the first logical block address collection; and
update the offset value associated with at least the first logical block address collection.

4. The system of claim 1 , wherein, the processor is further configured to, in response to determining to swap physical locations of the data stored at logical block address in the first logical block address collection and physical locations of the data stored at logical block addresses in the second logical block address collection:
increase a value of a first permanent write counter associated with the first logical block address collection by the value of the first transient write counter; and
increase a value of a second permanent write counter associated with the second block collection by the value of the second transient write counter.

5. The system of claim 1 , further comprising:
a data storage device comprising:
the plurality of memory devices; and
the processor.

6. The system of claim 1 , further comprising:
a data storage device comprising the plurality of memory devices; and
a host device comprising the processor.

7. The system of claim 1 , wherein the processor is further configured to:
in further response to determining to swap the physical locations of the data stored at logical block addresses in the first logical block address collection and the physical locations of the data stored at logical block addresses in the second logical block address collection:
set the value of the first transient counter and the value of the second transient write counter equal to a baseline value.

8. A method comprising: determining, by a processor, based on a value of a first transient write counter associated with a first logical block address collection and a value of a second transient write counter second logical block address collection associated, whether to swap physical locations of data stored in the first logical block address collection and physical locations of data stored in the second logical block address collection, wherein: the value of the first transient write counter equals a number of times data has been written to the first logical block address collection since a prior data swap involving the first logical block address collection, and the value of the second transient write counter equals a number of times data has been written to the second logical block address collection since a prior data swap involving the second logical block address collections and in response to determining to swap the physical locations of the data stored at logical block addresses in the first logical block address collection and the physical locations of the data stored at logical block addresses in the second logical block address collection: causing, by the processor, the physical locations of the data stored at the logical block addresses in the first logical block address collection to be swapped with the physical locations of the data stored at the logical block addresses in the second logical block address collection; and
wherein determining whether to swap physical locations of the data stored at logical block addresses in the first logical block address collection and physical locations of the data stored at logical block addresses in the second logical block address collection comprises: summing, by the processor, the value of the first transient write counter with a value of a first permanent write counter associated with the first logical block address collection to determine a first total write value indicating a total number of writes to the first logical block address collection, wherein the value of the first permanent write counter equals the number of times data was written to the first logical block address collectio

Assignees

• Western Digital Tech Inc

Inventors

• Kamruzzaman Md

Classifications

• G06F12/0238 Primary

  Memory management in non-volatile memory, e.g. resistive RAM or ferroelectric memory · CPC title

• G06F2212/657

  Virtual address space management · CPC title

• G06F12/109 Primary

  for multiple virtual address spaces, e.g. segmentation (G06F12/1036 takes precedence) · CPC title

• G06F12/0253

  Garbage collection, i.e. reclamation of unreferenced memory · CPC title

• G06F2212/7201

  Logical to physical mapping or translation of blocks or pages · CPC title