Split Actuator Disk Drive Concurrent Command Execution
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Solution Overview
Problem
Conventional disk drives operate at lower performance due to serial execution of access commands, which limits throughput and increases power consumption, as they do not efficiently utilize concurrent execution of access commands by multiple actuators.
Innovation Solution
Implementing a split actuator design with two voice coil motors (VCMs) that rotate actuator arms about a common pivot, allowing concurrent execution of access commands by derating seek profiles based on the time remaining for the other actuator to finish, thereby reducing power consumption while maintaining throughput performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If serial execution of access commands is used, then device complexity is reduced, but productivity decreases
Solution Approach 1:
The patent divides the actuator system into multiple independent actuators (first actuator and second actuator), each capable of independently executing access commands. This segmentation enables parallel execution of commands, thereby increasing throughput without requiring a single complex actuator to handle all commands sequentially.
2Productivity
If serial execution of access commands is used, then power consumption is reduced, but productivity decreases
Solution Approach 1:
The patent implements dynamic seek profile adjustment where the control circuitry monitors the execution status of access commands and dynamically modifies seek velocities. When one actuator completes its command earlier than the other, the control circuitry derates the seek profile of the faster actuator to match the completion time of the slower actuator, thereby enabling concurrent execution while managing power consumption efficiently.
3Productivity
If concurrent execution of access commands is implemented, then productivity improves, but device complexity increases
Solution Approach 1:
The patent employs feedback mechanisms where the control circuitry continuously monitors the execution progress of access commands by both actuators. Based on this feedback, the control circuitry dynamically adjusts seek profiles to ensure synchronized completion, thereby managing the complexity of concurrent execution through intelligent control rather than hardware complexity.
4Productivity
If concurrent execution of access commands is implemented, then power consumption increases, but productivity improves
Solution Approach 1:
The patent changes the operational parameters of the actuators by implementing derated seek profiles. When concurrent execution is enabled, the control circuitry adjusts seek velocities and timing parameters dynamically, derating the seek profile of actuators that would otherwise complete their commands earlier. This parameter adjustment allows concurrent execution to achieve throughput improvement while managing power consumption through optimized velocity profiles rather than running all actuators at maximum speed simultaneously.
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 enables concurrent execution of access commands, reducing power consumption while ensuring the same throughput as serial execution, by adjusting seek velocities and profiles dynamically based on the time remaining for other actuators to complete their tasks.
Implementation Method 1
a head connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM)
Data Source
AI summary
A data storage device is disclosed comprising a plurality of disk surfaces, a first plurality of heads actuated over a first subset of the disk surfaces by a first actuator, and a second plurality of heads actuated over a second subset of the disk surfaces by a second actuator. A first access command is executed using the first actuator and a second access command is executed using the second actuator. When the first access command finishes before the second access command finishes, a third access command is selected to execute using the first actuator based on a time remaining (To2) to finish the second access command, and at least part of the second access command is executed while concurrently executing at least part of the third access command during To2.