NVMe Controller Read-Retry Timing Optimization
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Solution Overview
Problem
Current NVMe standards face challenges in efficiently managing read-retry operations in non-volatile storage systems, leading to increased latency and reduced system performance due to unpredictable host response times and lack of optimized retry timing strategies.
Innovation Solution
A storage system and method that utilize a controller to gather statistics on host response times for prior commands, selecting an optimal retry time based on these statistics, and communicating this time to the host to minimize read-retry duration, thereby improving system performance and quality of service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional NVMe read-retry operations are used without optimized retry timing, then the storage system can handle command interruptions, but the read-retry duration increases and system performance decreases due to unpredictable host response times
Solution Approach 1:
The storage system implements a feedback mechanism by gathering statistics on host response times for prior commands. The controller monitors and records the actual response times of the host when retrying aborted commands, then uses this statistical data to dynamically determine optimal retry timing for future commands. This closed-loop feedback system enables the storage system to adapt to host behavior patterns and minimize read-retry duration, thereby resolving the contradiction between reducing time loss and maintaining system performance.
Solution Approach 2:
The invention applies preliminary action by pre-calculating and communicating optimal retry timing to the host before the actual retry operation occurs. Based on gathered statistics about host response patterns, the storage system determines the best retry time in advance and notifies the host accordingly. This allows the host to prepare and execute the retry operation at the optimal moment, reducing unnecessary waiting time and improving overall system performance without requiring complex real-time decision-making during the retry process.
2Loss of time
If retry timing is selected based on statistical analysis of host response times, then read-retry duration is reduced, but the controller complexity increases due to statistics gathering and analysis mechanisms
Solution Approach 1:
The storage system applies self-service by autonomously gathering and analyzing its own operational statistics without requiring external intervention or complex external systems. The controller internally monitors host response times, maintains statistical data about retry patterns, and independently determines optimal retry timing based on this self-collected information. This self-service approach reduces read-retry duration while avoiding the need for additional external complexity, as the system uses its own operational data to optimize its behavior.
Solution Approach 2:
The invention utilizes parameter changes by dynamically adjusting the retry timing parameter based on statistical analysis of host response times. Rather than using fixed retry intervals, the system modifies the retry timing parameter according to gathered statistics about when the host actually responds to and processes commands. This parameter adaptation enables the system to reduce read-retry duration by aligning retry operations with actual host availability patterns, while the complexity is managed through focused statistical tracking of key temporal parameters.
Data Source
AI summary
A storage system and method for reducing read-retry duration are provided. In one embodiment, a storage system is provided comprising a memory and a controller. The controller is configured to: receive a command from a host; and in response to an interruption in processing of the command: select a time for the host to retry the command, wherein the time is selected based on an expected host response time; and communicate the selected time to the host. Other embodiments are provided.