SSD Open Time Reduction via Segmented L2P Replay
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Solution Overview
Problem
The open time of memory devices, particularly solid-state drives (SSDs), is prolonged due to the time-consuming process of loading and replaying the logical-to-physical address mapping table and journal buffers during power-on sequences, which is exacerbated by the increasing size of these tables with storage capacity and the need for complete journal replay in case of sudden power-offs.
Innovation Solution
Dividing the logical-to-physical address mapping table into segments, assigning separate journal buffers to each segment, and recreating segments in a power-on sequence by replaying corresponding journal buffers, with a device-ready signal sent upon successful recreation of initial segments, and recreating remaining segments in the background to reduce open time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the L2P address mapping table is fully loaded into DRAM during power-on sequence, then the device can access data immediately, but the open time is prolonged due to the large size of the mapping table
Solution Approach 1:
The L2P address mapping table is divided into multiple segments, each associated with a separate journal buffer. During power-on, only critical segments are replayed immediately while non-critical segments are replayed in the background, reducing the open time while maintaining data access capability.
Solution Approach 2:
Instead of replaying the entire L2P mapping table during power-on sequence, the system replays only the necessary portions (critical segments) immediately and handles the remaining segments in the background, achieving sufficient functionality with partial action.
2Reliability
If a complete journal replay is performed during sudden power-off recovery, then data integrity is ensured, but the open time is significantly increased
Solution Approach 1:
The journal is divided into multiple journal buffers, each corresponding to a segment of the L2P mapping table. This segmentation allows selective replay of only necessary journal buffers during power-on, ensuring data integrity for critical segments while reducing overall replay time.
Solution Approach 2:
The journal buffers are prepared and organized in advance during normal operation, allowing the system to quickly identify and replay only the necessary buffers during power-on sequence or sudden power-off recovery, rather than replaying the entire journal from scratch.
3Adaptability or versatility
If the L2P address mapping table size increases with storage capacity, then more addresses can be mapped, but the time to load and replay the table increases proportionally
Solution Approach 1:
The L2P address mapping table is segmented into multiple smaller units, each with its own journal buffer. This allows the system to handle large storage capacities while reducing the time required to load and replay mapping information by processing segments in parallel or in prioritized sequences.
Solution Approach 2:
The system introduces a new dimension of organization by associating each L2P segment with a dedicated journal buffer, creating a multi-dimensional structure that enables selective and parallel processing of different segments, thereby reducing overall processing time despite increased total size.
Data Source
AI summary
Provided are methods, apparatuses, systems, and computer-readable storage media for reducing an open time of a solid-state drive (SSD). In an embodiment, a method includes dividing a logical-to-physical (L2P) address mapping table of the SSD into a plurality of segments. The method further includes assigning one journal buffer of a plurality of journal buffers to each segment of the plurality of segments. The method further includes recreating, during a power on sequence of the SSD, a portion of the plurality of segments by replaying a first subset of the plurality of journal buffers. The method further includes sending, to a host device, a device-ready signal upon successful recreation of the portion of the plurality of segments. The method further includes recreating, in a background mode, a remaining portion of the plurality of segments by replaying a second subset of the plurality of journal buffers.