Media Cache Cleaning in Shingled Magnetic Recording Drives
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Solution Overview
Problem
In shingled magnetic recording (SMR) systems, the need for rewriting an entire band of data when changes occur in one or more cells leads to media cache saturation, especially in mobile environments with limited time for media cache cleaning due to Advanced Power Management (APM), resulting in system performance issues and slow throughput.
Innovation Solution
A power supply status detection mechanism that adjusts the APM value to enable either normal or aggressive media cache cleaning based on the power source, with aggressive cleaning triggered when AC power is detected and the media cache usage exceeds a threshold, ensuring efficient cleaning and power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aggressive media cache cleaning is performed to prevent cache saturation, then cache cleaning rate is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic adjustment of media cache cleaning aggressiveness based on detected power supply status. When AC power is detected, the system performs aggressive cleaning to prevent cache saturation. When battery power is detected, the system performs normal cleaning to conserve energy. This dynamic adaptation resolves the contradiction by making the cleaning rate variable rather than fixed.
Solution Approach 2:
The system changes the operational parameters of media cache cleaning based on power supply conditions. The cleaning aggressiveness parameter is adjusted: high aggressiveness when AC power is available, normal aggressiveness when battery power is available. This parameter change allows the system to optimize between cleaning rate and power consumption under different operating conditions.
2Use of energy by moving object
If normal media cache cleaning is performed to save power, then power consumption is reduced, but cache saturation risk increases
Solution Approach 1:
The system dynamically adjusts cleaning aggressiveness based on power supply detection. When AC power is detected, it switches from normal cleaning to aggressive cleaning, thereby reducing cache saturation risk when power is abundant. This dynamic switching resolves the contradiction by adapting cleaning intensity to available power resources.
Solution Approach 2:
The system uses feedback from power supply status detection to adjust media cache cleaning behavior. The detection mechanism provides continuous feedback about available power, and the cleaning aggressiveness is adjusted in response to this feedback. This closed-loop control prevents cache saturation while managing power consumption effectively.
3Quantity of substance
If shingled magnetic recording is used to increase cell density, then storage capacity is improved, but media cache saturation occurs more frequently
Solution Approach 1:
The system changes the cleaning aggressiveness parameter in response to power supply conditions to manage the increased cache saturation frequency caused by SMR. When AC power is available, aggressive cleaning is performed to handle the higher saturation rate. This parameter adjustment allows the system to accommodate SMR's higher storage capacity while managing its increased cache management demands.
Data Source
AI summary
Implementations disclosed herein provide a method comprising detecting a power supply status, determining a media cache cleaning scheme based on the detected power supply status, and performing the determined cleaning scheme until a predetermined threshold is reached.