Block Group Tagging for Flash Memory Metadata Reduction
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Solution Overview
Problem
Flash-memory systems face challenges in efficiently handling page-specific metadata due to the need for extensive storage space and RAM, as each page requires individual metadata entries, leading to increased complexity and resource requirements.
Innovation Solution
Implementing a tag-grouping mechanism that associates multiple blocks with shared metadata values, allowing blocks with similar writing times to be grouped, reducing the need for individual metadata storage per block and enabling accurate approximation of metadata values across blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If page-specific metadata is stored for each page individually, then measurement precision of page-specific characteristics is improved, but device complexity and memory requirements increase significantly
Solution Approach 1:
The patent merges multiple blocks into a block group and stores metadata at the group level rather than individually for each block. The controller maintains a block group mapping table that maps block group identifiers to metadata, allowing multiple blocks to share common metadata entries. This reduces the overall number of metadata entries from potentially thousands (if stored per-page) to a manageable number (stored per-block-group), significantly reducing device complexity while maintaining the ability to track page-specific characteristics through the hierarchical mapping structure.
Solution Approach 2:
The patent segments the storage hierarchy into multiple levels: pages within blocks, blocks within block groups, and block groups with shared metadata. This segmentation allows the system to manage page-specific metadata efficiently by organizing it hierarchically - common metadata is stored at the block-group level while page-specific variations are handled through the mapping structure. This segmented approach reduces redundancy and simplifies the storage system compared to flat per-page metadata storage.
2Reliability
If individual metadata entries are maintained for each block, then reliability of block-specific information is improved, but loss of substance (storage space) increases
Solution Approach 1:
The patent combines multiple blocks into block groups and stores a single set of metadata entries for the entire group rather than maintaining separate metadata for each block. The block group mapping table establishes the relationship between block group identifiers and metadata, allowing the system to retrieve appropriate metadata for any block within the group. This merging approach significantly reduces the total metadata storage space required in flash memory while maintaining reliable block-specific information through the mapping structure that links individual blocks to their group's metadata.
3Device complexity
If metadata storage is reduced by grouping blocks, then device complexity is reduced, but measurement precision of individual block characteristics may deteriorate
Solution Approach 1:
The patent implements a hierarchical segmentation where block groups serve as containers for multiple blocks, and a block group mapping table provides the linkage between groups and individual blocks. This segmentation allows metadata to be stored at the block-group level (reducing complexity) while the mapping table preserves the ability to access and differentiate individual block characteristics when needed. The mapping structure acts as an intermediary layer that maintains measurement precision for individual blocks without requiring separate metadata entries for each block.
Data Source
AI summary
Embodiments described herein disclose methods, devices, and media for storing data. Methods including the steps of: receiving data to be stored in a memory that includes at least three blocks, wherein each block, for storing the data, has at least one metadata value, associated with each block, that is dependent upon a writing time of each block; grouping at least three blocks into at least two block groups, wherein at least one block group contains at least two blocks; associating a respective metadata value with each block group; and associating the respective metadata value of a respective block group with each block storing the data contained in the respective block group, without storing a dedicated copy of at least one metadata value for each block. In some embodiments, at least one metadata value is stored in a block-group table.