Dynamic Host-Copy Migration Rate Control via MPIO Feedback
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Solution Overview
Problem
Host-copy migration in storage systems often negatively affects foreground IO servicing due to unrestricted resource utilization, making it difficult to differentiate between foreground and background IOs and maintain efficient data migration without degrading processing.
Innovation Solution
A method and apparatus that measure baseline and reference response times for foreground data access during host-copy migration, adjusting the data transmission rate to minimize the impact on foreground IOs by distinguishing between foreground and background IOs using an MPIO driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If host-copy migration is performed at high data transmission rate, then migration efficiency is improved, but foreground IO response time deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of data transmission rate during host-copy migration based on real-time monitoring of foreground IO response times. The system transitions from static to dynamic control by continuously measuring response times and adjusting migration throughput accordingly, ensuring migration efficiency is maximized without degrading foreground IO performance below acceptable thresholds.
Solution Approach 2:
The patent employs feedback control mechanisms where foreground IO response times are continuously monitored and used to adjust the host-copy migration data transmission rate. The system measures baseline response times, compares them against threshold values, and dynamically modifies migration throughput based on the feedback from performance measurements, creating a closed-loop control system that balances migration efficiency with foreground IO performance.
2Loss of time
If static limits are placed on host-copy IO rate, then foreground IO performance is protected, but migration completion time increases
Solution Approach 1:
The patent replaces static throttling limits with dynamic rate adjustment that adapts to actual system conditions. Instead of applying fixed constraints that always limit migration speed, the system continuously monitors foreground IO response times and adjusts migration throughput in real-time, allowing higher rates when foreground performance is good and reducing rates only when necessary, thereby minimizing migration completion time while protecting foreground IO performance.
Solution Approach 2:
The patent changes the migration data transmission rate parameter dynamically based on measured foreground IO response times. Rather than maintaining a constant conservative rate, the system adjusts this critical parameter in response to changing system conditions, increasing the rate when foreground performance allows and decreasing it when foreground IO response times deteriorate, thus optimizing both migration speed and foreground performance.
Data Source
AI summary
A multi-path input-output (MPIO) driver in a host server reduces host-copy migration data transmission rate based on decrease in foreground IO response time. A baseline foreground IO response time measured before commencement of the host-copy migration is compared with a reference foreground IO response time measured after commencement of the host-copy migration. Increase in the foreground IO response time, expressed as a percentage or time value, that satisfies a predetermined limit will trigger reduction of the host-copy migration data transmission rate. The reference foreground IO response time is repeatedly measured and updated each time the host-copy migration data transmission rate is decreased.