SSD Controller XOR Recovery Data Discrepancy Detection

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Solution Overview

Problem

Data storage devices, such as solid state drives (SSDs), face issues with data integrity loss during XOR recovery due to bit errors, leading to mis-compare events where incorrect or outdated data is transferred to a host device without detection.

Innovation Solution

A data storage device with a controller comprising an XOR module, ECC module, scrambler, encoder, and comparison logic is configured to decode, encode, and compare data, executing additional XOR protection logic if the difference between encoded and retrieved data exceeds a threshold, ensuring accurate data transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If XOR recovery is used to correct bit errors, then data reliability is improved, but data integrity may be lost due to undetected mis-compare events

Engineering Contradiction:

Improvedata reliabilityVSAvoiddata integrity

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent implements a feedback mechanism by comparing the encoded version of recovered data against the original retrieved data. The comparison logic detects discrepancies and triggers additional XOR recovery operations when mismatches are found, creating a closed-loop system that continuously verifies data integrity after recovery operations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary comparison mechanism that acts as a mediator between the XOR recovery process and the host device. The encoder and comparison logic serve as intermediaries that verify the correctness of recovered data before it is returned to the host, preventing undetected data corruption.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If additional XOR protection logic is executed, then data integrity is improved, but device complexity increases

Engineering Contradiction:

Improvedata integrityVSAvoidcontroller complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by encoding the decoded data before the host device receives it. The encoder prepares the data in advance, and the comparison logic is ready to immediately verify the encoded data against the original retrieved data, preventing mis-compare events before they reach the host device.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If data is returned to host device without verification, then processing speed is improved, but mis-compare events occur

Engineering Contradiction:

Improvedata transfer speedVSAvoiddata accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent performs preliminary encoding and comparison operations before returning data to the host device. The encoder encodes the decoded data and the comparison logic verifies it against the original retrieved data, ensuring data accuracy is checked in advance before the data leaves the storage device.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11537466B2Detection of data discrepancy after XOR recovery

Publication Date: 2022.12.27 SANDISK TECHNOLOGIES LLC

AI summary

A data storage device includes a memory device and a controller coupled to the memory device. The controller comprises an XOR module, an ECC module, a scrambler, an encoder, and comparison logic. The controller is configured to retrieve data from the memory device, decode the retrieved data, execute XOR protection logic on the decoded data, encode the decoded data, and compare the encoded data to the retrieved data stored in the memory device.