Design And Implementation Of The Recovery And Online Capacity Expansion For RAID

With the widely use of information technology, the demand on capacity is driven by explosively increasing information, and the demand on reliability of the storage system is becoming even more as there exists various risks. So how to increase the capacity of RAID with least cost, ensure the system reliability without sevice performance decline, and overcome the speed bottleneck are becoming more and more important in storage world.In order to improve the reliability of the system, we focus on the recovery mechanism. Popularity-Based Reconstruction Optimization algorithm is implemented based on the research of the characteristic of existing reconstruction algorithms and the workloads. Such algorithm reconstructs the regions which users frequently visit as soon as possible to reduce the disk head movement for reducing the user response time and the reconstruction time. Implement read-redirection as the original one doesn't need to reconstruction-read when the requests fall on the replace disk only until the reconstruction completes, avoid double synchronous write. The result demonstrates that PRO implemented on Linux OS greatly outperforms the original one in terms of the OLTP applications workload which is read/write-mixed and small I/O requests-dominant.Increasing data require much more online storage. Design Online Capacity Expansion according the order and implement it in our RAID abstract layer. It makes users increase the capacity of the RAID system by adding new disks or using bigger disks to copy and replace the original disks, while they do not need to close and restart their system, backup their data or stop their using. Online Capacity Expansion Technology improves the scalability of RAID greatly.