Storage Controller Write Skipping for Lower Flash Write Amplification

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Solution Overview

Problem

Storage devices with NAND flash memory experience irregular performance due to write amplification (WAF) and slow flush operations, necessitating improved WAF characteristics and increased flush operation speed.

Innovation Solution

A storage controller with a write amplification (WAF) manager that checks for invalid data before the final programming step and a central processing unit (CPU) that skips unnecessary programming, along with a memory cell compactor that moves memory cells to avoid open cells, thereby optimizing programming operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the storage controller performs N-times programming of memory cells to ensure data reliability, then the reliability of data storage is improved, but the write amplification increases and flush operation speed decreases

Engineering Contradiction:

Improvedata storage reliabilityVSAvoidflush operation speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The WAF manager performs preliminary checking of data validity before the Nth programming operation. By checking whether data is invalid (e.g., trailing zeros pattern) in advance, the system can skip unnecessary programming operations, thereby reducing write amplification and improving flush speed while maintaining reliability for valid data

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses the data's own characteristics (invalid data patterns) to determine whether programming should be performed. The WAF manager autonomously identifies invalid data and prevents unnecessary programming without requiring external intervention, thus improving efficiency

Inventive Principle:

Principle #25Self-service

2Reliability

If the storage controller performs multiple programming operations to ensure data integrity, then the data integrity is improved, but the energy consumption increases

Engineering Contradiction:

Improvedata integrityVSAvoidprogramming energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The WAF manager performs preliminary validation checking before executing the energy-intensive Nth programming operation. By identifying invalid data patterns in advance, the system avoids consuming energy on unnecessary programming operations while maintaining data integrity for valid data

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system discards unnecessary programming operations for invalid data, recovering the energy that would have been consumed. This selective discarding approach maintains energy efficiency while preserving data integrity for valid data

Inventive Principle:

Principle #34Discarding and recovering

Data Source

PatentUS12525285B2Storage controller with improved write amplification characteristics and storage device including the same

Publication Date: 2026.01.13 SAMSUNG ELECTRONICS CO LTD

AI summary

A storage controller for writing first data to a first memory cell by performing programming of the first memory cell N-times, where N is a positive integer greater than 1, includes a write amplification manager and a central processing unit. The write amplification manager checks whether the first data is invalid data before an Nth programming of the first memory cell is performed, and the central processing unit does not perform the N-th programming of the first memory cell when the first data is the invalid data.