SSD L2P Table Paging for Faster Boot and Low Idle Power
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Solution Overview
Problem
Current solid state drives (SSDs) have lengthy boot-up times due to the time-consuming firmware initialization phase, particularly the loading of the logical-to-physical (L2P) indirection table, and consume power even during idle states, which is inefficient for battery-powered devices.
Innovation Solution
The SSD defers loading the L2P table until after booting and pages it out to NAND during idle time, allowing for sequential or on-demand loading of table segments, enabling the SSD to power down during idle periods and resume quickly, thus reducing boot-up time and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the L2P table is loaded during firmware initialization, then the boot-up process is complete, but the boot-up time becomes excessively long
Solution Approach 1:
The L2P table is paged out to NAND memory during idle time before the boot-up process occurs. This preliminary action allows the table to be prepared in advance, so that during boot-up only a partial boot is needed without loading the entire L2P table, significantly reducing boot-up time while ensuring the table is ready when needed.
Solution Approach 2:
The L2P table is divided into multiple segments that can be loaded sequentially or on-demand. Instead of loading the entire table during boot-up, only necessary segments are loaded, allowing the boot process to complete faster while the remaining segments are loaded as needed during operation.
2Productivity
If the SSD remains powered on to maintain state, then the SSD is ready to service IO requests, but power consumption increases during idle states
Solution Approach 1:
The SSD implements dynamic power management by entering a powered-down state during idle periods and resuming quickly when IO requests are received. The L2P table segments are paged out to NAND memory during idle time, allowing the SSD to maintain data state without continuous power, thus reducing idle power consumption while ensuring rapid resumption of operations.
3Use of energy by stationary object
If the L2P table is paged out to NAND during idle time, then power consumption is reduced, but access latency may increase when loading table segments
Solution Approach 1:
The L2P table segments are paged out to NAND memory during idle time before they are needed. This preliminary action ensures that when IO requests arrive, the required table segments are already available or can be quickly loaded from NAND, minimizing access latency while maintaining low idle power consumption.
Solution Approach 2:
The L2P table is segmented and stored in NAND memory during idle periods. When access is needed, only the specific segments required for the current IO operation are loaded from NAND to the L2P indirection table in memory, reducing both the amount of data that needs to be accessed and the overall access latency compared to loading the entire table.
Data Source
AI summary
Various embodiments are directed to apparatuses and methods for faster solid state drive (SSD) boot-up. On boot-up, SSD control algorithms may load non-logical to physical (L2P) parts of a context and signal the system that the SSD is ready. The context may comprise various state data pertaining to the SSD. After signaling that the SSD may be ready to receive access requests, the SSD control algorithms may begin loading segments of the L2P table sequentially. Access to the L2P table may be blocked, however, when a requested segment has not yet been loaded. In such cases, the SSD control algorithms may then load the requested segment out of turn and then service the access request.