Nonvolatile Memory Copy History for Hot-Cold Data Segregation

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Solution Overview

Problem

The mixing of hot and cold data in a nonvolatile memory block leads to a decrease in the efficiency of garbage collection (GC) operations, as it becomes difficult to determine the type of data and manage them effectively, resulting in reduced efficiency and increased wear on the memory system.

Innovation Solution

A memory system that includes a controller which writes data and history information to a block, where the history information is based on the number of times the data has been copied, allowing the system to distinguish between hot and cold data, thereby optimizing GC operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If hot data and cold data are mixed together in a same block of the nonvolatile memory, then the storage capacity is maximized, but the efficiency of garbage collection decreases

Engineering Contradiction:
Improvestorage capacityVSAvoidgarbage collection efficiency
Core Design Contradiction:
Quantity of substanceVSProductivity

Solution Approach 1:

The patent segments data into hot data and cold data based on write frequency characteristics, and stores them in separate blocks. The controller tracks write counts for each data page and identifies hot/cold data accordingly, then performs garbage collection separately for each data type, preventing mixing in the same block.

Inventive Principle:
Principle #1Segmentation

2Quantity of substance

If hot data and cold data are mixed together in a same block of the nonvolatile memory, then the storage capacity is maximized, but the wear on the memory system increases

Engineering Contradiction:
Improvestorage capacityVSAvoidmemory system wear
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent segments data into hot data and cold data based on write frequency characteristics, and stores them in separate blocks. The controller tracks write counts for each data page and identifies hot/cold data accordingly, then performs garbage collection separately for each data type, preventing mixing in the same block.

Inventive Principle:
Principle #1Segmentation

3Quantity of substance

If hot data and cold data are mixed together in a same block of the nonvolatile memory, then the storage capacity is maximized, but the difficulty of determining data type increases

Engineering Contradiction:
Improvestorage capacityVSAvoiddata type identification
Core Design Contradiction:
Quantity of substanceVSDifficulty of detecting and measuring

Solution Approach 1:

The patent implements a feedback mechanism where the controller continuously monitors write counts for each data page, uses this information to classify data as hot or cold, and adjusts garbage collection operations accordingly. The write count information serves as feedback that enables automatic data type identification and appropriate block management.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4711936A1Memory system and method of controlling nonvolatile memory
Publication Date: 2026.03.18 KIOXIA CORP
  • EP4711936A1 patent drawingFigure 1
  • EP4711936A1 patent drawingFigure 2
  • EP4711936A1 patent drawingFigure 3

AI summary

According to one embodiment, a memory system (1) includes a controller (30) configured to write data and history information to one of a plurality of blocks. In copying first data that is valid data stored in a copy source block, to a copy destination block, the controller (30) reads the first data and first history information from the copy source block, the first history information being history information corresponding to the first data, and writes the read first data and second history information to the copy destination block. The second history information is based on a value of the read first history information.