Illusory Free Space Calculation for Consistent SSD Performance
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Solution Overview
Problem
Solid state drive (SSD) devices with varying numbers of usable and unusable blocks due to different yields during production lead to inconsistent performance across devices, affecting endurance and uniformity.
Innovation Solution
Implementing a mechanism to calculate and utilize 'illusory free space' by subtracting spare blocks from actual free blocks, ensuring all devices appear to have the same number of free blocks, thereby synchronizing relocation operations and maintaining consistent performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If additional spare blocks are used as free blocks for storing data during runtime, then endurance benefit is provided, but device-to-device performance variance increases
Solution Approach 1:
The patent changes the parameter used for monitoring free blocks from actual physical free blocks to a calculated illusory free space value. This parameter change allows the system to maintain consistent performance thresholds across devices while still utilizing all available blocks including spare blocks for endurance benefits.
Solution Approach 2:
The patent introduces an intermediary calculation layer between the physical blocks and the performance monitoring system. The controller calculates illusory free space by subtracting additional spare blocks from actual free blocks, creating a virtual representation that masks the underlying hardware variations while preserving endurance benefits.
2Ease of manufacture
If devices have different numbers of usable and unusable blocks due to production yields, then manufacturing flexibility is improved, but device-to-device performance uniformity deteriorates
Solution Approach 1:
The patent transforms the performance monitoring parameter from actual block count to illusory free space calculation, allowing devices with different manufacturing yields to be treated uniformly. This enables production flexibility while achieving performance uniformity through software-based parameter transformation.
Solution Approach 2:
The patent creates equipotential conditions across devices with different manufacturing characteristics by using a normalized illusory free space metric. All devices operate from the same reference point regardless of their actual block variations, achieving performance uniformity without restricting manufacturing flexibility.
3Measurement precision
If actual free blocks are used for performance monitoring, then accurate representation of available storage is provided, but performance variance between devices increases
Solution Approach 1:
The patent introduces illusory free space as an intermediary metric between actual physical blocks and performance monitoring. This intermediary layer provides accurate enough representation for performance control while masking device-to-device variations, achieving both measurement adequacy and performance consistency.
Solution Approach 2:
The patent changes the monitoring parameter from actual free blocks to illusory free space calculated by subtracting additional spare blocks. This parameter transformation maintains sufficient accuracy for performance monitoring while eliminating the source of device-to-device performance variance.
Data Source
AI summary
Data storage devices having the same capacity but with a different number of spare blocks and a different number of unusable blocks may cause device-to-device performance variance. This variance may be minimized by using illusory free blocks for relocation while using actual free blocks for other operations. In this regard, each data storage device having the same storage capacity may include a corresponding number of unusable blocks and a corresponding controller. Each controller may obtain a minimum number of blocks for supporting a predetermined storage characteristic. Each controller may calculate a respective number of spare blocks based on a respective number of unusable blocks, perform relocation for the respective data storage device based on the minimum number of blocks, and perform operations, which are not relocation, based on the minimum number of blocks and the respective number of spare blocks.