Storage Controller QoS Management via Dual-Memory Threshold Updates
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Solution Overview
Problem
Existing storage devices struggle to accurately check the upper limit of access without degrading IO performance when providing storage access services by grouping logical devices, as they lack effective inter-controller communication and shared operation information management.
Innovation Solution
The storage device employs a dual-memory system with in-controller and inter-controller shared memory to manage IO operations, using a processor to fetch and compare IO requests against upper limit values, and adjust execution counts to maintain accurate QoS control without degrading performance by minimizing inter-controller shared memory access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inter-controller shared memory is accessed frequently to check IO execution counts, then measurement precision of upper limit control is improved, but IO performance is degraded due to increased memory access overhead
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing threshold values in the operation information table before IO operations occur. The threshold represents a predetermined condition (e.g., 80% of upper limit) that triggers updates to inter-controller shared memory. This allows the system to maintain accurate upper limit control while avoiding frequent memory accesses, as updates only occur when the threshold is reached rather than after every IO operation.
2Adaptability or versatility
If QoS control is implemented across multiple controllers with shared memory, then adaptability of service grouping is improved, but device complexity increases due to inter-controller communication requirements
Solution Approach 1:
The patent implements universality by creating a standardized operation information table structure and inter-controller communication mechanism that can be applied to any QoS group regardless of the number of controllers or logical devices involved. The same table format and update thresholds work universally across different storage device configurations, allowing flexible service grouping without requiring controller-specific customization. This multi-functional approach enables the system to adapt to various service scenarios while maintaining consistent control logic.
Data Source
AI summary
The number of QoS group execution IO with respect to a logical device is retained in both of an inter-controller shared memory and an in-controller shared memory. Then, a processor of a storage device compares the number of in-controller execution IO with an update interval threshold value set by the following expression.Update Interval Threshold Value=(“QoS Group IOUpper Limit Value”−(“Number of QoS Group Execution IO” in In-Controller Shared Memory+“Number of In-Controller Execution IO”))דMargin Ratio Coefficient”÷“Number of Controllers in System”Then, the processor adds the number of in-controller execution IO to the number of QoS group execution IO of the inter-controller shared memory when the number of in-controller execution IO is greater than or equal to the update interval threshold value, and performs rewriting in the inter-controller shared memory.