Research And Implementation Of File System Virtualization In Multi-kernel Operating System

China's total data center market has reached 9.2 billion US dollars in 2010,and maintained double-digit growth rate in recent years.With the rapid expansion of the data center,the demand for software and hardware is also increasing.The traditional Monolithic kernel operating system like Linux has been unable to adapt to the rapid growth of hardware,and the extra virtualization cost of traditional virtualization method has affected the application execution efficiency seriously,so the multi-kernel operating system RainForest appears.However,due to the limitations of disk controller,disk resources can not be shared to multiple kernels at the same time,this thesis presents a method called file system virtualization to solve multiple kernel disk access problems.Network file system NFS(network file system)is a common solution in this case,it can forward requests to other kernels through network,and return the results of the request,but the network transmission rate's performance is so bad that performance of NFS is very weak,and with increased number of requests and concurrency,performance of NFS degrade very serious.The characters of data center application are high concurrency and big data,NFS can not meet the request of multi-kernel operating system for disk access.Therefore,processing capacity of the file system virtualization proposed in this thesis for large data volume concurrent requests is especially important.According to the above requirements,the design and coding of the file system is based on the FUSE(file system in user space)file system in multiple kernels to build front-end,and these kernels can access a disk at the same time through the front-end.The main work done is as follows:(1)the full use of multi-thread to achieve file system virtualization,allocate threads to process tasks according to the number of requests.(2)using thread-pool technology to reduce the cost of threads create and destroy.(3)using shared memory to transmit data between kernels,greatly reducing the overhead from transmission.(4)using interrupt and polling as the notification mechanism to reduce the overhead of virtualizationThe file system virtualization of Multi-kernel operating system achieve all operations to access disk like read,write,link,delete,modify permissions and so on,you can run all the large-scale applications which access disk frequently like Hadoop,parsec,etc.and the performance is much better than the traditional solution NFS,the file system virtualization make the multi-kernel operating system RainForest more perfect and more suitable for modern data center.