Nonvolatile Memory Block Group Defect Management
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Solution Overview
Problem
Current memory systems face challenges in efficiently managing defective physical blocks within nonvolatile memory, leading to suboptimal data writing and reading performance due to the need to skip defective blocks, which complicates address mapping and increases the amount of information required for notification to the host.
Innovation Solution
A memory system with a controller that allocates block groups and writes data into non-defective physical blocks, skipping defective blocks, and notifies the host with a reduced set of information including a bitmap indicating defective blocks, allowing for efficient data placement and management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the host is notified of detailed information about defective blocks and address mapping, then data integrity is maintained, but the amount of information required for notification increases and complexity of address mapping increases
Solution Approach 1:
The patent introduces a bitmap as an intermediary data structure that indirectly represents the mapping between logical blocks and physical blocks. Instead of providing detailed address mapping information to the host, the controller uses a compact bitmap where each bit corresponds to a physical block group, indicating whether defective blocks are present. This intermediary representation maintains data integrity by enabling the controller to handle defective blocks while presenting a simplified interface to the host.
Solution Approach 2:
The patent changes the parameter of information representation from detailed address mapping data to a compact bitmap structure. By transforming the notification mechanism from providing extensive address mapping information to sending a condensed bitmap with deficit information, the system reduces the volume of notification data while maintaining the ability to ensure data integrity through the bitmap's defect indication capability.
2Manufacturing precision
If detailed address mapping information is provided to the host, then data placement accuracy is improved, but the amount of information required for notification increases
Solution Approach 1:
The patent extracts only the essential information needed for data placement from the complete address mapping data. Instead of notifying the host of all address mapping details, the system extracts and communicates only the deficit information through the bitmap - specifically, which physical block groups contain defective blocks. This extraction approach maintains data placement accuracy by providing sufficient information for the controller to manage defective blocks while minimizing notification information volume.
Solution Approach 2:
The patent transforms the notification parameter from comprehensive address mapping information to a condensed bitmap representation. This parameter change reduces the information volume significantly while preserving the critical data placement accuracy requirement, as the bitmap enables the controller to identify and skip defective blocks during data operations.
3Reliability
If defective blocks are skipped during data writing, then data integrity is maintained, but the complexity of managing block groups increases
Solution Approach 1:
The patent segments the physical blocks into multiple block groups and introduces a bitmap structure to manage these segments. Each bit in the bitmap corresponds to a specific physical block group, allowing the controller to independently track and manage defective blocks within each group. This segmentation approach maintains data integrity by enabling systematic skipping of defective blocks while organizing the management complexity into manageable, discrete units through the bitmap's structured representation.
Data Source
AI summary
According to one embodiment, a memory system writes first write data into each non-defective physical block belonging to a first write destination block group. The memory system notifies a host of a first identifier of the first write data, an address specifying the first write destination block group, a first offset indicating a top write destination physical storage location in the first write destination block group in which the first write data is written, length of the first write data, and first bitmap information including a plurality of bits, each of the bits corresponding to each of physical blocks belonging to the first write destination block group and indicating whether or not the corresponding physical block is a defective block.