Background IO Scheduler Latency Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In log structured storage systems, background operations such as garbage collection, deduplication, and drive rebuilds are resource-intensive and impact performance by causing contention with host IOs, leading to unpredictable behavior due to lack of coordination between host IO scheduling and background operations.
Innovation Solution
A scheduler that monitors host IO latency and dynamically adjusts background IO operations based on normalized mean calibrated latency, prioritizing and throttling IOs to minimize impact on host performance, using a multi-priority queue mechanism and Quality of Service (QoS) settings to orchestrate scheduling and regulate internal operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If background operations (garbage collection, deduplication, rebuilds) are performed resource-intensively, then storage system maintenance and data integrity are improved, but host IO performance deteriorates due to resource contention
Solution Approach 1:
The patent implements dynamic adjustment of background operation rates based on real-time host IO latency measurements. The system continuously monitors latency metrics and adjusts the intensity of background operations (garbage collection, deduplication, rebuilds) to match current host performance conditions, ensuring background tasks are accelerated when host IO is light and throttled when host IO is heavy, thus resolving the contradiction between maintaining data integrity and preserving host IO performance
Solution Approach 2:
The system employs a feedback mechanism where host IO latency is continuously measured and used to regulate background operation rates. The latency metrics serve as feedback signals that trigger adjustments in background task intensity, creating a closed-loop control system that automatically balances background maintenance needs against host performance requirements, preventing resource contention while ensuring storage system reliability
2Stability of the object's composition
If background operations are coordinated with host IO scheduling, then system stability is improved, but scheduling complexity increases due to multi-priority queue management
Solution Approach 1:
The patent segments the IO scheduling system into multiple priority queues (e.g., high, medium, low priority) that separate host IO operations from background operations. This segmentation allows independent management and scheduling of different operation types, reducing interference between them and improving system stability. The multi-queue structure enables targeted control policies for each queue type, managing complexity through organized separation rather than monolithic scheduling
Solution Approach 2:
The patent introduces an intermediary scheduling layer that acts as a mediator between host IO requests and background operations. This intermediary scheduler monitors system state and makes intelligent routing decisions, prioritizing host IO when necessary while allowing background operations to proceed when resources are available. The mediator absorbs scheduling complexity by implementing policy-based routing and priority management, shielding higher-level components from low-level scheduling intricacies
3Duration of action of stationary object
If background IO rate is increased to complete maintenance tasks faster, then storage system availability is improved, but host response time deteriorates due to resource contention
Solution Approach 1:
The patent dynamically changes the operational parameters of background tasks based on system state. When host response time metrics indicate good performance, the system increases background IO rates to accelerate maintenance completion. When host response time deteriorates, the system reduces background IO rates to preserve host performance. This parameter adjustment strategy enables flexible optimization of both maintenance speed and host responsiveness without fixed trade-offs
Data Source
AI summary
A method, computer program product, and computer system for receiving an indication about an amount of background IOs a background scheduler is capable of performing on a plurality of applications, wherein the indication may be based upon, at least in part, one of host IO latency and a rate of the host IO latency being at one of a plurality of levels. One or more applications of the plurality of applications on which to perform the background IOs may be determined. The background IO applications to be performed on the one or more applications of the plurality of applications may be scheduled based upon, at least in part, one of the host IO latency and the rate of the host IO latency being at one of the plurality of levels.