Non-Volatile Memory Data Compaction via Offset Preservation
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Solution Overview
Problem
Modern SSDs and NAND flash memory systems face performance and endurance issues due to the processing burden of garbage collection, which involves extra writing and address updates necessary for data relocation and reuse, leading to inefficiencies in managing compaction and space allocation.
Innovation Solution
A method and system that compact data by copying valid data from a source block to a destination block while writing new data to the same offset positions previously occupied by obsolete data, minimizing the need for control data writing and updating only the coarse granularity mapping table, thereby reducing the processing burden of garbage collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If garbage collection is performed by copying valid data to a new block and updating address mappings, then space is created for reuse, but processing burden increases and performance decreases
Solution Approach 1:
The patent extracts the address update operation from the data copying operation. By maintaining a separate mapping table that is updated independently, the system eliminates the need to update address mappings for every data copy, thereby reducing the processing burden while still achieving space creation for reuse
Solution Approach 2:
The patent introduces a mapping table as an intermediary between the physical data blocks and the logical address space. This mapping table absorbs the complexity of tracking data locations, allowing the garbage collection process to focus solely on copying valid data without the overhead of simultaneous address updates
2Loss of information
If address update data is written to track relocated data, then data location tracking is maintained, but control data writing overhead increases
Solution Approach 1:
The patent creates a separate copy of the mapping table that is dedicated to tracking relocated data during garbage collection. This copy allows the system to maintain accurate address tracking information without writing update data back to the main storage, thereby reducing control data writing overhead
Data Source
AI summary
A system and method for compacting data in a non-volatile memory system that may reduce the need for control data updates is described. The method may include copying valid data from a source block to a destination block, and also writing new host data to the destination block, such that the offset position in the destination block of the copied data is the same as in the source block and fewer mapping table updates are needed for the copied data. The system may include a non-volatile memory system with a coarse granularity mapping table and a fine granularity mapping table where a controller in the non-volatile memory system is configured to only update the coarse granularity mapping table for compacted data written to a new block, but is configured to update both the fine and coarse granularity mapping tables for new host data written to the new block.