Storage Controller RAID Operating Rate Calculation
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Solution Overview
Problem
Storage systems face challenges in accurately determining the operating status of physical devices within a RAID group, as some devices do not provide information on their operating statuses, making it difficult to calculate the system load and manage I/O loads effectively.
Innovation Solution
A storage controller measures the RAID group operating time and corrects it using a correction coefficient based on the type of physical devices and backend multiplicity of I/O commands, allowing for the calculation of an appropriate operating rate without requiring information from the devices themselves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If information indicating operating statuses is acquired from PDEVs, then measurement precision of operating status is improved, but some PDEVs having no function to transmit such information cannot provide the information
Solution Approach 1:
The patent introduces a storage controller as an intermediary that calculates the operating status of PDEVs indirectly. Instead of requiring direct status information transmission from PDEVs, the storage controller measures I/O operation data (read/write counts, transfer amounts) and computes operating status metrics, thereby resolving the contradiction between measurement precision and compatibility with non-transmitting devices
Solution Approach 2:
The storage controller performs self-service by autonomously calculating PDEV operating status based on I/O operation records it maintains. The controller uses its own stored information about I/O commands issued to PDEVs to derive operating status metrics without requiring external information from the PDEVs themselves, thus eliminating the need for PDEV transmission functions
2Productivity
If RG operating rate is calculated based on PDEV operating statuses, then productivity of storage system management is improved, but device complexity increases due to need to monitor multiple PDEVs
Solution Approach 1:
The patent merges the monitoring function into the storage controller that already manages I/O operations. By combining the I/O command issuance function with the operating status calculation function in a single controller, the system avoids the complexity of separate monitoring mechanisms for each PDEV, achieving efficient RG operating rate calculation without proportional increases in system complexity
3Measurement precision
If correction coefficient is applied to RG operating time, then measurement precision of operating rate is improved, but device complexity increases due to additional calculation parameters
Solution Approach 1:
The patent applies parameter changes by introducing a correction coefficient that adjusts the RG operating time based on the ratio of actual I/O operations to total I/O commands. This parameter modification allows the system to account for idle time and non-operational periods, improving operating rate measurement precision while maintaining relatively simple calculation logic within the storage controller
Data Source
AI summary
A storage controller measures a RAID group (RG) operating time, which is the operating time of an RG. The storage controller then corrects the measured RG operating time, which is used to calculate the operating rate of the RG, on the basis of a correction coefficient associated with the type of the physical devices (PDEVs) constituting the RG, and on the basis of the RG backend multiplicity, which is the multiplicity of the I/O commands transmitted to the RG.