Research Of Data Consistency Protection Mechanism In Dual-controller Active-active RAID System

In the big data era,the importance of data is highlighted everywhere.Dual-Controller RAID(Redundant Array of Independent Disks)device,which provides high performance,stability and reliability data storage services for users,has been the important unit of storage system.Therefore,it is widely used in various data centers.In practical application,Dual-Controller RAID system constructed by Linux software MD(Multiple-Devices Driver)is adopted.Working in Active-Active mode,the concurrent disk operation of the two controllers on the same stripe will lead the data/parity data to an inconsistency due to the stripe cache in the internal of MD.As for this issue,a kind of safeguard mechanism to guarantee data consistency in Dual-Controller RAID system which works under the operating mode of Active-Active is designed and implemented,and provides protections of data consistency on RAID devices.In this mechanism,the whole disk space in RAID storage system is fixed to logical blocks with the same size.And then,the consultation solution,the request-respond negotiation strategy between two controllers is adopted to consult the operation right of logic block,and when one of the two controllers that wants to access data in a logic block without the operation right needs to request the operation right of the logic block from the other,then the requested controller must migrate the operation right to the request controller after finishing the whole active operations in the logic block,and the operation right will be kept by the request until the next request order about this logic block comes from the other.Additionally,for reducing the impact of requesting the logic block operation right on I/Os(Input/Output),the model of interaction communication for Dual-Controller RAID is designed and implemented,and provides some necessary functions such as the high-speed information exchanges,to monitor the system states,to handle the system errors and so on.It is presented by the experiments that the mechanism protects the data consistency in Dual-Controller Active-Active RAID system,and the mechanism gets a 4% performance loss,comparing with that of the original single-controller RAID system.The result indicates the adopted strategy is feasible within the acceptable range.