SSD L2P Mapping Copying to Reduce Data Transfer Time
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Solution Overview
Problem
The performance of data copying in solid state disks (SSDs) is restricted due to the need for multiple read and write operations and data transmission across the system bus during the file copying process.
Innovation Solution
The method involves converting logical addresses to logical page addresses (LPAs) and incrementing reference counts of physical addresses to copy L2P values, replacing actual data copying with mapping table operations, and managing the Gppa_Reference_Count table to recycle physical addresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data is copied by reading from source and writing to target sequentially, then data integrity is ensured, but copying speed is greatly restricted due to multiple read-write operations and system bus transmissions
Solution Approach 1:
The patent copies L2P mapping entries from source to target within the SSD's memory instead of copying actual data through the system bus. This involves reading L2P entries from the source logical address range, converting them to target logical addresses, and writing them to the target L2P table, thereby achieving data copying through mapping table operations rather than physical data transmission
Solution Approach 2:
The L2P mapping table serves as an intermediary structure that enables indirect data copying. Instead of directly transferring user data between source and target, the system uses L2P mappings as an intermediate layer to redirect logical addresses to the same physical data locations, allowing the SSD to present copied data to the host without actual data movement
2Productivity
If multiple read-write operations are performed on NAND, then data is accurately copied, but the performance is restricted due to NAND's write-after-erase requirement and multiple access cycles
Solution Approach 1:
The patent copies L2P mapping table entries instead of actual data, performing read operations on source L2P entries and write operations on target L2P entries within the SSD's memory subsystem. This eliminates the need for multiple NAND erase and program cycles that would be required if actual data were copied, significantly reducing operation complexity and improving performance
Solution Approach 2:
The patent segments the data copying process into two distinct phases: L2P mapping table copying (performed within SSD memory) and actual data validation (performed on-demand by the host). This segmentation allows the bulk copying operation to proceed quickly through mapping table manipulation while deferring complex NAND operations to when actually needed
Data Source
AI summary
A method for copying data quickly, includes: obtaining, by a host computer, a logical address of a target data to be copied and a logical address of a source data; sending, by the host computer, a data copying command to a SSD; converting, by the SSD, the logical address range of the target data and the logical address range of the source data into a LPA range of the target data and a LPA range of the source data; sequentially copies, by the SSD, L2P values corresponding to the LPA range of the source data to L2P values corresponding to the LPA range of target data; incrementing, by the SSD, a reference count of a physical address corresponding to the LPA range of the source data to indicate that the data has been copied; and transmitting a signal indicating that the data has been copied to the host computer.