Nonvolatile Memory Controller SPO Recovery via Partial Decoding

Solution Overview

Problem

Data storage devices face challenges in recovering quickly from sudden power off (SPO) events, leading to increased recovery time and potential data damage due to unnecessary decoding and read disturbances.

Innovation Solution

A data storage device with a nonvolatile memory and controller that scans for erased pages without decoding, performs simple decoding for system data, and uses duplicate data blocks to recover failed data, limiting decoding to hard decision decoding to minimize recovery time and prevent data damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If full decoding is performed for all read data during recovery operation, then data recovery reliability is improved, but recovery time increases and read disturbance damage occurs

Engineering Contradiction:

Improvedata recovery reliabilityVSAvoidrecovery time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies partial decoding by performing only hard decision decoding (HDD) on system data during recovery operation, rather than full decoding. This partial action is sufficient to detect errors and determine whether pages are erased, while avoiding the time-consuming soft decision decoding (SDC) process. The principle resolves the contradiction by providing just enough decoding to achieve reliable error detection without the excessive time cost of complete decoding.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent segments the decoding process into two distinct stages: a fast scanning stage using only hard decision decoding to identify erased pages, and a subsequent stage where full decoding is applied only to specific pages that require recovery. This segmentation allows the system to quickly process large amounts of data to locate problems, then apply intensive decoding only where necessary, thereby reducing overall recovery time while maintaining reliability.

Inventive Principle:

Principle #1Segmentation

2Reliability

If full decoding is performed for all read data during recovery operation, then data recovery reliability is improved, but read count increases causing data damage

Engineering Contradiction:

Improvedata recovery reliabilityVSAvoidread disturbance damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies partial decoding by performing only hard decision decoding on system data during recovery operation, rather than full decoding. This partial action is sufficient to detect errors and determine whether pages are erased, while avoiding the time-consuming soft decision decoding (SDC) process. The principle resolves the contradiction by providing just enough decoding to achieve reliable error detection without the excessive time cost of complete decoding.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent segments the decoding process into two distinct stages: a fast scanning stage using only hard decision decoding to identify erased pages, and a subsequent stage where full decoding is applied only to specific pages that require recovery. This segmentation allows the system to quickly process large amounts of data to locate problems, then apply intensive decoding only where necessary, thereby reducing overall recovery time while maintaining reliability.

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If scanning with decoding is performed to detect erased pages, then detection accuracy is improved, but processing speed decreases

Engineering Contradiction:

Improveerased page detection accuracyVSAvoidscanning speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent applies partial decoding by performing only hard decision decoding on system data during recovery operation, rather than full decoding. This partial action is sufficient to detect errors and determine whether pages are erased, while avoiding the time-consuming soft decision decoding (SDC) process. The principle resolves the contradiction by providing just enough decoding to achieve reliable error detection without the excessive time cost of complete decoding.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS10824523B2Data storage device and operating method thereof

Publication Date: 2020.11.03 SK HYNIX INC

AI summary

A data storage device includes a nonvolatile memory device and a controller which controls the nonvolatile memory device. When the data storage device is powered on after a sudden power off (SPO), the controller detects an erased page by scanning, without decoding, a first system data block of a nonvolatile memory device, performs simple decoding for first system data of first system pages before the erased page, and, if the simple decoding is a fail, recovers the first system data for which the simple decoding failed, by reading out second system data from corresponding second system pages of a second system data block as a duplicate block of the first system data block.