A Method of Shared File Cache for File Clone Function to Improve I/O Performance for Virtual Machines

We propose a method for shared file cache function for cloned files used by virtual machines, called SCC. The file clone function copies the files faster than conventional (read and write) method. Moreover, the function reduces disk spaces. The function is used to deploy virtual machines in virtual desktop infrastructure because of fast copying a lot of virtual machine disk files. SCC uses the file cache of a shared file as a shared cache among cloned files. The cached data on the shared file are returned to application programs on accessing the shared file via cloned files. Therefore, SCC improves the I/O performance of the shared file due to avoiding disk accesses. In this paper, we implement SCC and evaluate the I/O performance. From the evaluation, we have found SCC improves I/O throughput about 38 times in the case of random read and shared cache hit.