Garbage Collection Method for Data Storage Devices with Limited DRAM
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Solution Overview
Problem
In data storage devices without sufficient DRAM, the entire logical to physical (L2P) mapping table cannot be stored, leading to inefficiencies in garbage collection, where source blocks may not be reliably released as spare blocks due to overflow issues during data transfer.
Innovation Solution
A garbage collection method that selects source blocks with valid data exceeding a predetermined threshold, copies data into a destination block, updates the mapping table, and recovers source blocks as spare blocks, ensuring efficient use of destination blocks and increasing spare block availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the entire L2P mapping table is divided into sub-L2P mapping tables and exchanged into a small DRAM for garbage collection, then the device can operate with limited DRAM capacity, but source blocks may not be reliably released as spare blocks due to overflow issues during data transfer
Solution Approach 1:
The L2P mapping table is divided into multiple sub-L2P mapping tables, each managing a specific range of logical addresses. This segmentation allows the system to work with smaller, manageable table portions in limited DRAM while ensuring complete source block release through proper tracking of valid data locations across all sub-tables
Solution Approach 2:
The system implements feedback mechanisms by continuously tracking the number of valid data pages in each source block and comparing it against the destination block capacity. This feedback ensures that garbage collection operations complete successfully and source blocks can be reliably released as spare blocks
2Productivity
If valid data of source blocks is filled to exceed destination block capacity as much as possible, then data storage efficiency is improved, but there is no guarantee that source blocks can be released into spare blocks after garbage collection
Solution Approach 1:
The system dynamically adjusts the garbage collection strategy by changing parameters such as the number of source blocks to collect, the destination block selection, and the data copying quantity. These parameter changes ensure that collection operations achieve high storage efficiency while maintaining the reliability of source block release by adapting to real-time device state
Data Source
AI summary
A garbage collection method is provided and applied to a data storage device. The garbage collection method includes the following steps: selecting source blocks from data blocks, wherein a total number of valid data of the source blocks is larger than or equal to a predetermined data number of a block; copying valid data of a part of the source blocks into a destination block, wherein a total number of the valid data of the part of the source blocks is smaller than the predetermined data number; copying all or a part of valid data of remaining source blocks into the destination block; updating a logical to physical addresses mapping table based on a mapping information of the destination block; and recovering all or a part of the source blocks as spare blocks.