Memory Controller Super-Block Classification for Random Write Performance

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Solution Overview

Problem

Existing storage devices face challenges in efficiently managing reserved regions to improve performance and reliability, particularly in non-volatile memory systems like SSDs, due to the increasing demand for high-performance and high-reliability storage solutions.

Innovation Solution

A memory controller is employed to determine and replace initial bad blocks with reserved blocks, update a bad block bitmap, and classify super blocks as free or reserved based on the number of bad blocks, allowing for efficient management of reserved regions and allocation for writing operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If reserved blocks are allocated for replacing bad blocks, then reliability is improved, but random write performance deteriorates due to limited available blocks

Engineering Contradiction:

Improvestorage device reliabilityVSAvoidrandom write performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent dynamically adjusts the number of reserved blocks based on the actual bad block replacement rate. The memory controller monitors how many bad blocks occur in practice and adjusts the reserved block allocation accordingly, transforming a static reserved region into a dynamic one that adapts to actual usage patterns, thereby improving random write performance while maintaining reliability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of reserved block quantity from a fixed value to a variable that can be adjusted based on monitoring data. By changing this parameter dynamically, the system optimizes the balance between having enough reserved blocks for reliability and having enough free blocks for write performance

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If a fixed number of reserved blocks are allocated, then management simplicity is improved, but resource utilization efficiency deteriorates

Engineering Contradiction:

Improvereserved region managementVSAvoidusable storage capacity

Core Design Contradiction:

Ease of operationVSQuantity of substance

Solution Approach 1:

The memory controller automatically monitors bad block occurrences and adjusts the reserved region size without external intervention. The system self-manages the reserved blocks by monitoring actual bad block rates and dynamically allocating appropriate amounts, eliminating the need for manual configuration while optimizing resource utilization

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent performs preliminary monitoring of bad block rates during initial operation and uses this data to pre-adjust the reserved region size before it becomes a constraint on storage capacity. By taking preliminary action to monitor and adjust, the system avoids the problem of fixed allocation limiting usable capacity

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250251868A1Memory controller, storage device including memory controller, and method of operating the same

Publication Date: 2025.08.07 SAMSUNG ELECTRONICS CO LTD

AI summary

A memory controller replaces a bad block of a given super block with a reserved block, and updates a bad block bitmap. The memory controller includes a super block classifier configured to determine the given super block as a free block or a reserved block according to a number of bad blocks of the given super block. When the given super block is determined as the free block, memory controller inserts an identifier of the given super block into a free block list.