Research On Implementation And Optimization Of Hybrid Storage System Bcache Base On Linux

As we enter the era of big data, data volume and server volume grows, the growth trend of storage systems become lower cost and higher performance. However, each individual media storage system, like mechanical hard disk, solid state disk or non volatile random memory has different limits, and can not meet the needs of storage system. Mechanical hard disk has advantage of low cost and low price, but read and write performance is poor.Hybrid storage system can make full use of the characteristics of mechanical hard disk and solid state disk, and it can improve the storage system performance. The open source framework Bcache is a hybrid storage technology.This thesis first introduces the research status and development of hybrid storage technology, and then analyzes the key technologies in hybrid storage. Then, the thesis studies two kinds of hybrid storage system based on Linux, Flashcache and Bcache algorithm. Then we analyze the two algorithms in four aspects, mapping strategy, cache replacement policy, read/write processes and garbage collection mechanism, and the experimental results show that the Bcache algorithm is better than the Flashcache algorithm.Based on analyzing Bcache algorithm, we propose an improved Bcache algorithm based on the Bcache algorithm to solve the problem, such as the problem of the parallel processing, the speed adjustment, the write delay and the performance of the system. For parallelism problems system, lock mechanism of B + tree is optimized, with increasing the thread pool based optimization queue, which will increase the degree of parallelism and reduces thread switching between threads wasted system resources. For the problems in the write-back of write-back rate, control algorithm is optimized, we proposed a combination of an exponentially weighted average PID control algorithm and proposed a new method to solve the writeback process IO delay is too large. For Bcache random read performance bottlenecks, we design an efficient and secure page caching mechanism given the realization. Finally, the performance of the system is analyzed by using different file block sizes and different IO depth, and Verify that we do on Bcache optimization.