Heterogeneous Nonvolatile Memory Storage with Uniform Metadata Distribution
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Solution Overview
Problem
Flash memory devices face challenges in using block erase operations, which hinder their application as main system RAM or conventional hard-disk file systems, and require additional wear-leveling and metadata management to extend their lifetime and improve performance.
Innovation Solution
A data storage device using two or more heterogeneous nonvolatile memory cells, where metadata and user data are stored in a uniformly-distributed manner across memory blocks selected in a round-robin fashion, eliminating the need for separate wear-leveling operations and extending the device's lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If block erase operation is performed in flash memory, then data can be written to the memory, but the erase time is greater than write time and it hinders use as main system RAM
Solution Approach 1:
The flash memory is divided into multiple data storage areas with different characteristics (e.g., SLC and MLC regions). By segmenting the memory into zones with different erase/write speed characteristics, the system can perform writes in faster regions without requiring full-block erases, thereby reducing erase time while maintaining data storage capability.
Solution Approach 2:
The patent implements a dynamic memory management system that adaptively selects which data storage area to use based on current operation requirements. The controller dynamically switches between different memory regions, using faster areas for frequent writes and slower areas for less critical data, thereby optimizing the balance between write speed and erase time.
2Adaptability or versatility
If conventional hard-disk file system is used with flash memory, then data storage is enabled, but block erase operations hinder performance and require additional wear-leveling management
Solution Approach 1:
The patent introduces a flash translation layer (FTL) that acts as an intermediary between the conventional hard-disk file system and the flash memory's block erase requirements. The FTL translates file system write operations into appropriate flash memory operations, managing wear-leveling and block erases transparently, thereby maintaining file system compatibility while reducing the complexity burden on the host system.
Solution Approach 2:
The controller is designed to support multiple file systems and access modes, making it universally compatible with different host systems. By implementing a multi-functional controller that can handle both conventional file system operations and native flash operations, the patent reduces the need for specialized wear-leveling management in each specific application.
3Ease of operation
If metadata is stored in a single predetermined memory block, then address mapping is simplified, but the memory block suffers from repeated program-erase operations reducing its lifetime
Solution Approach 1:
The patent segments the metadata storage function across multiple data storage areas rather than concentrating it in a single block. Different types of metadata (e.g., primary mapping information, secondary mapping information, and management data) are distributed across different memory regions, which prevents any single block from being repeatedly erased and extends overall system lifetime while maintaining address mapping functionality.
Solution Approach 2:
The system implements a metadata management mechanism where old or less frequently accessed metadata is moved to slower memory areas, and frequently accessed metadata is maintained in faster areas. This rotation and recovery strategy ensures that no single memory block is continuously overwritten, extending its operational lifetime while maintaining ease of address mapping for active data.
Data Source
AI summary
Provided is a data storage device including two or more data storage areas including may have two or more (heterogeneous) types of nonvolatile memory cells. At least one of the data storage areas includes a plurality of memory blocks that are sequentially selected, and metadata are stored in the currently selected memory block. The memory blocks can be sequentially used and metadata can be stored in a uniformly-distributed manner throughout the data storage device. Therefore, separate merging and wear-leveling operations are unnecessary. Thus, it is possible to improve the lifetime and writing performance of a data storage device having two or more heterogeneous nonvolatile memories.