Host-Managed SSD L2P Mapping for Lower-Latency Data Access
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Solution Overview
Problem
Host devices are subject to latency and lack control over SSD operations due to internal SSD controller bottlenecks, leading to unpredictable latency in data access and management of SSD operations such as garbage collection and health monitoring.
Innovation Solution
Host devices manage SSD data addressing and I/O scheduling by maintaining an L2P table, gaining insights into SSD storage structure and operational health, allowing coherent data processing and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the SSD controller maintains the L2P table internally, then the SSD can manage address mapping autonomously, but the host device experiences latency and lacks control over SSD operations
Solution Approach 1:
The patent extracts the L2P table management function from the SSD controller and relocates it to the host device. The host device now maintains the L2P table and provides it to the SSD controller, which only performs address translation based on the host-provided mapping. This extraction gives the host full control over address management and eliminates the latency caused by controller-side table maintenance.
Solution Approach 2:
The host device acts as an intermediary between the logical address space and the physical storage medium. By maintaining the L2P table and providing it to the controller, the host mediates the address translation process, enabling both logical addressing for applications and efficient physical address management without controller bottlenecks.
2Loss of information
If the L2P table is maintained by the SSD controller, then address mapping is managed autonomously, but the host device cannot gain insights into SSD storage structure and operational health
Solution Approach 1:
By maintaining the L2P table, the host device gains visibility into the SSD's storage structure and can monitor operational health through the mapping information. The host can track which logical addresses map to which physical blocks, enabling insights into storage utilization, wear patterns, and operational status. This feedback loop allows the host to make informed decisions about data management and SSD health monitoring.
Solution Approach 2:
The host device performs the L2P table maintenance itself rather than relying on the controller to provide this information. The host actively manages the address mapping, which enables it to gain insights into storage structure while the controller focuses on its core function of data transfer and basic operations.
3Productivity
If the host device manages L2P addressing, then data access speed and latency are improved, but the host device must maintain additional data structures
Solution Approach 1:
The host device maintains the L2P table in advance, populating it with address mappings before data access operations occur. This preliminary action ensures that when data needs to be accessed, the mapping is already available in the host's memory, eliminating the need for real-time translation and improving access speed. The host prepares the address mapping information proactively rather than reactively.
Data Source
AI summary
A host device may determine a storage structure of a storage medium of a solid state drive (SSD). The host device may determine a physical block address to be used by a logical block address based on determining the storage structure. The host device may generate a logical 2 physical (L2P) entry that maps the physical block address to the logical block address. The host device may store the L2P entry in an L2P data structure that is stored in a first memory of a host device, wherein a copy of the L2P data structure in a second memory of a controller of the SSD. The host device may provide, to the controller, the physical block address and the logical block address. The addresses may be provided to perform a write operation or a read operation at a physical location, of the storage medium, identified by the physical block address.