Flash Memory Host Interface Logical Block Fragmentation Control

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Solution Overview

Problem

Flash memory systems face inefficiencies in data storage and management due to fragmentation, where obsolete data occupies valuable space, and frequent data consolidation is needed to reclaim space, degrading system performance, especially when storage capacity is close to the addressable limit.

Innovation Solution

Implementing a direct data file management system that allocates data from a host to memory cell blocks in a manner that limits the number of blocks per file, reducing fragmentation by mapping logical blocks to physical blocks with similar storage capacity, and allowing the host to configure the logical address space to match physical memory characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If data are stored in flash memory using traditional LBA interface, then the host can access data through continuous logical address space, but data fragmentation occurs and obsolete data occupies valuable space

Engineering Contradiction:

Improvehost access through continuous logical address spaceVSAvoidstorage capacity utilization

Core Design Contradiction:

Ease of operationVSQuantity of substance

Solution Approach 1:

The patent segments the continuous logical address space into discrete logical blocks that correspond to physical memory blocks. Each logical block can be independently managed and mapped to physical blocks, enabling fine-grained control over data placement while maintaining the simplicity of sequential address access for the host.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a logical block as an intermediary layer between the host's continuous logical address space and the physical flash memory blocks. This intermediary enables the host to access data through simple sequential addresses while the system manages the mapping to physical blocks, handling fragmentation and obsolete data reclamation automatically.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If data consolidation is performed frequently to reclaim space, then storage capacity is maintained, but system performance degrades

Engineering Contradiction:

Improveavailable storage capacityVSAvoidsystem performance

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The patent performs preliminary actions by pre-allocating logical blocks to physical blocks during data writing operations. This ensures that data is placed in optimal locations from the beginning, reducing the need for subsequent consolidation operations and maintaining performance even as storage fills up.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a mechanism to discard obsolete data references and recover physical blocks for reuse. When data is deleted or overwritten, the system discards the old logical-to-physical mappings and recovers the physical blocks, making them available for new data without requiring full consolidation operations.

Inventive Principle:

Principle #34Discarding and recovering

3Quantity of substance

If the number of blocks per file is limited, then data fragmentation is reduced, but flexibility in data allocation is constrained

Engineering Contradiction:

Improvedata consolidation efficiencyVSAvoiddata allocation flexibility

Core Design Contradiction:

Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic mapping where the number of logical blocks per file is not fixed but adapts based on the actual data size and physical block availability. The system can create multiple logical blocks for a single file if needed, or consolidate them when possible, providing flexibility while maintaining the benefit of block-level management.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent makes logical blocks universal by allowing them to serve multiple files and multiple physical blocks. A single logical block can be mapped to different physical blocks at different times, and a physical block can store data from multiple logical blocks, providing versatile reuse while maintaining efficient fragmentation control.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Loss of time

If logical blocks are mapped to physical blocks with similar storage capacity, then data relocation is minimized, but mapping complexity increases

Engineering Contradiction:

Improvedata relocation timeVSAvoidlogical-to-physical mapping complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent changes the parameter of block size matching by configuring logical blocks to have the same size as physical blocks. This parameter change simplifies the mapping relationship and enables direct one-to-one correspondence, minimizing data relocation while keeping the mapping table manageable through standard flash block sizes.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7917686B2Host system with direct data file interface configurability

Publication Date: 2011.03.29 PALISADE TECH LLP

AI summary

Data files are assigned addresses within one or more logical blocks of a continuous logical address space interface (LBA interface) of a usual type of flash memory system with physical memory cell blocks. This assignment may be done by the host device which typically, but not necessarily, generates the data files. The number of logical blocks containing data of any one file is controlled in a manner that reduces the amount of fragmentation of file data within the physical memory blocks, thereby to maintain good memory performance. The host may configure the logical blocks of the address space in response to learning the physical characteristics of a memory to which it is connected.