Multi-Actuator Disk Queue Allocation for Faster Host Response
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Solution Overview
Problem
Existing magnetic disk devices with multiple actuator systems face challenges in efficiently managing simultaneous disk access and internal processing, leading to decreased response speed to host commands due to allocation of internal processing tasks.
Innovation Solution
The magnetic disk device employs a controller to allocate internal processing commands to actuator systems with fewer host commands, using a dedicated LUN for internal processing and optimizing command queues to minimize response time delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If internal processing tasks are allocated to actuator systems during simultaneous disk access, then internal processing can be performed, but the response speed to host commands decreases
Solution Approach 1:
The patent segments the actuator systems into multiple independent groups, with each group having its own control queue. This allows internal processing commands and host commands to be processed in separate segments without interfering with each other, resolving the contradiction between performing internal processing and maintaining fast response to host commands.
Solution Approach 2:
The controller dynamically selects which actuator system group to allocate internal processing commands to, based on the current state of command queues. This dynamic allocation ensures that internal processing is performed on underutilized actuator systems, preventing degradation of host command response speed.
2Productivity
If multiple actuator systems are used for simultaneous disk access, then disk access efficiency is improved, but managing internal processing becomes complex
Solution Approach 1:
The patent divides the plurality of actuator systems into multiple groups, with each group having a dedicated control queue. This segmentation simplifies command management by providing a clear structure for allocating and tracking commands, reducing the complexity of managing internal processing across multiple actuator systems while maintaining simultaneous disk access efficiency.
Solution Approach 2:
The controller acts as an intermediary that manages the allocation of internal processing commands to actuator system groups. It monitors the state of each control queue and makes intelligent allocation decisions, simplifying the overall management complexity while enabling efficient utilization of multiple actuator systems for both disk access and internal processing.
Data Source
AI summary
According to one embodiment, a memory of a magnetic disk device includes a plurality of control queues respectively corresponding to a plurality of actuator systems. A controller receives a plurality of first commands from a host, and stores the plurality of first commands in one of the plurality of control queues. The controller generates a second command for internal processing, and stores the second command in a first control queue that stores a smallest number of commands among the plurality of control queues. The controller executes, for each of the plurality of control queues, processing one or more commands stored in one control queue of the plurality of control queues by using an actuator system corresponding to the one control queue among the plurality of actuator systems.