Dynamic RAID Rebuild Processing Size Control
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Solution Overview
Problem
Current RAID systems face performance issues and increased completion time for Rebuild/Copy back processing, especially when normal I/O requests are absent, due to fixed processing sizes that do not adapt to load status, leading to suboptimal disk device performance.
Innovation Solution
A RAID system and method that dynamically adjust the processing size for Rebuild/Copy back operations based on the presence of normal I/O requests, increasing the size when no normal I/O requests are received for a predetermined time to enhance processing efficiency and reduce completion time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed processing size is used for Rebuild/Copy back operations, then processing simplicity is maintained, but completion time increases when no normal I/O requests are present
Solution Approach 1:
The patent applies dynamics by making the processing size adjustable rather than fixed. The control unit dynamically changes the processing size based on whether normal I/O requests are present, allowing the system to adapt between two operational modes: normal mode (smaller processing size when I/O requests exist) and rebuild mode (larger processing size when no I/O requests are present), thereby reducing completion time without significantly increasing complexity
Solution Approach 2:
The patent changes the parameter of processing size based on system state. When normal I/O requests are detected, the control unit uses a first processing size; when no normal I/O requests are detected for a predetermined time, it switches to a second processing size that is larger than the first. This parameter change optimizes the balance between maintaining normal operations and accelerating rebuild/copy back processes
2Productivity
If larger processing size is used for Rebuild/Copy back operations, then processing speed increases, but impact on normal I/O performance increases
Solution Approach 1:
The system dynamically adjusts processing size based on the presence of normal I/O requests. When normal I/O requests are detected, the control unit uses a smaller processing size to minimize impact on normal operations. When no normal I/O requests are detected for a predetermined time, it switches to a larger processing size to maximize rebuild/copy back speed, thus balancing productivity and reliability through dynamic adaptation
Solution Approach 2:
The control unit periodically checks for the presence of normal I/O requests and switches processing size accordingly. This periodic monitoring and adjustment ensures that the system maintains optimal performance for both normal operations and rebuild/copy back processes by timing the use of larger processing sizes to periods when normal I/O activity is absent
Data Source
AI summary
A RAID system access a physical disk according to a host I/O request, and perform Rebuild/Copy back processing, for implementing high-speed Rebuild/Copy back processing without interrupting the processing of a normal I/O. When one disk device out of a plurality of disk devices constituting the RAID configuration fails, the processing size for one time of Rebuild/Copy back to reconstruct the RAID is changed according to the presence of a normal I/O managed in RAID control. When a normal I/O is present, Rebuild/Copy back can be executed without interrupting the processing of the normal I/O, and in a static state where a normal I/O is absent, a processing size larger than the size in that state can be specified so as to implement Rebuild/Copy back processing at high-speed.