Storage Device Command Scheduling for Seek Energy Optimization
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Solution Overview
Problem
Existing data storage devices face challenges in optimizing seek operations to balance performance and energy efficiency, particularly in managing seek energy differences and cache storage space effectively.
Innovation Solution
The implementation of control circuitry that selects a target command and a free command based on seek energy differences and cache availability, dynamically adjusting the seek energy difference threshold to optimize performance and power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the data storage device seeks directly to the target command location, then the access time is reduced and performance is improved, but the energy consumption increases
Solution Approach 1:
The control circuitry identifies and executes free commands that can be performed during the seek time to the target command. By preparing and executing these preliminary operations during the inevitable seek operation, the system utilizes otherwise wasted time productively, improving overall throughput without additional seek operations
Solution Approach 2:
The system dynamically adjusts the threshold for selecting free commands based on current device state, including cache status and workload characteristics. This dynamic adaptation allows the system to optimize the balance between executing free commands and maintaining direct seeks to target commands under varying operational conditions
2Productivity
If the data storage device executes free commands during seek time, then productivity is improved, but the seek energy consumption increases
Solution Approach 1:
The control circuitry changes the parameter of command selection by evaluating multiple candidate free commands and selecting those that minimize additional energy consumption. The system adjusts which free commands are executed based on their energy cost versus productivity benefit, dynamically optimizing the trade-off between throughput and energy usage
3Adaptability or versatility
If the control circuitry dynamically adjusts the seek energy difference threshold, then adaptability is improved, but device complexity increases
Solution Approach 1:
The control circuitry implements feedback mechanisms by monitoring the results of free command execution and adjusting the threshold for selecting future free commands. This feedback loop allows the system to learn from past decisions and optimize its behavior, improving adaptability while keeping the control logic manageable through rule-based adjustments
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the data storage device's ability to efficiently execute access commands by optimizing seek operations, reducing energy consumption, and maintaining optimal cache health.
Implementation Method 1
a magnetic storage medium such as a disk and a recording head connected to a distal end of an actuator arm that is rotated about a pivot by a voice coil motor (VCM)
Data Source
AI summary
A data storage device executes access commands received from a host by a recording head actuated over a magnetic storage medium. A target command is selected from queued host access commands. A free command is selected that can be executed during a time required for a seek from the recording head location to a target command location. A seek energy difference between the energy required to seek from the recording head location to a free command location to the target command location, and to seek from the recording head location directly to the target command location is determined. The device seeks to and executes the free and target commands if the seek energy difference is less than a threshold, and seeks directly to the target command if the seek energy difference is greater than the threshold.