Multi-Actuator Storage Device with Priority-Based Actuator Selection
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Solution Overview
Problem
Current multi-actuator storage devices experience significant drops in throughput when random I/Os interrupt sequential workloads, leading to inefficient data access and increased latency, as existing communication protocols fail to effectively manage actuator usage based on request priorities.
Innovation Solution
Implementing a multi-actuator design where separate actuators are optimized for either sequential or random access, with a priority bit determining which actuator to use for each request, allowing for asymmetric actuator configurations with one actuator reserved for sequential operations and another for random reads, and using a request distributor to route requests based on priority and access patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single actuator is used to handle both sequential and random I/O requests, then the device structure is simple, but throughput drops significantly when random I/Os interrupt sequential workloads
Solution Approach 1:
The patent divides the single actuator system into multiple independent actuators, where one actuator is dedicated to sequential I/O operations and another is dedicated to random I/O operations. This segmentation allows each actuator to specialize in its designated access pattern, preventing throughput degradation when random I/Os interrupt sequential workloads, while maintaining manageable device complexity through clear functional separation.
Solution Approach 2:
The patent applies local quality by optimizing each actuator for its specific access pattern: the sequential actuator is configured with features optimized for continuous data streaming (such as buffer caching strategies), while the random actuator is configured with features optimized for random access patterns (such as direct seek capabilities). This localized optimization ensures each actuator performs at peak efficiency for its designated workload type.
2Productivity
If separate actuators are optimized for sequential and random access, then throughput is maximized, but device complexity and cost increase
Solution Approach 1:
The patent implements asymmetry by making one actuator read-only while the other actuator handles both read and write operations. This asymmetric configuration reduces manufacturing costs because the read-only actuator can use simpler, less expensive components (such as read-only memory caches and simpler head assemblies), while the full-featured actuator handles all write operations. This approach maintains high throughput performance while reducing overall device complexity and manufacturing cost.
3Ease of operation
If actuator selection is based on request priority, then data access efficiency improves, but control complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring and pre-optimizing each actuator for its specific access pattern before operation begins. The sequential actuator is pre-configured with sequential access optimizations (such as buffered I/O pathways), and the random actuator is pre-configured with random access optimizations (such as direct memory mapping). This preliminary configuration eliminates the need for complex real-time decision-making during operation, as the actuator selection is determined by simple, pre-established rules based on the I/O request type, thereby improving data access efficiency without significantly increasing control complexity.
Data Source
AI summary
A multi-actuator storage device includes separate actuators that can be used to access a storage medium. A property of a request can be analyzed to determine which actuator to use to access data associated with the request. For example, high-priority requests can be handled by an actuator designated for random I/O requests, whereas low-priority requests can be handled by an actuator designated for sequential I/O requests. Writes can be treated as low-priority requests. In a particular embodiment, a priority bit can be used to determine which actuator is used to access the data.