Performance Improvement of File Operations on OverlayFS for Containers
Naoki Mizusawa, Joichiro Kon, Yuya Seki, Jian Tao, Saneyasu Yamaguchi · 2018
Server consolidation with virtualization is a popular method to address the issue of a large amount of power consumption of inter-connected computers in data centers. The more computers are consolidated, the more energy is saved. However, highly consolidating, wherein many servers are consolidated into one physical computer, results in large performance decline. Especially, I/O performance is severely decreased as reported. In this work, we focus on Docker, a popular container-based virtualizing system, and OverlayFS. OverlayFS is widely recognized method for improving I/O performance in Docker. First, we evaluate the performance of file operations on OverlayFS. In particular, we focus on the performance of file writing involving copy_up and show that the performance is severely low. Second, we investigate the performance and behavior the filesystem during copy_up and demonstrate that synchronization is the most important issue. Third, we discuss a method for improving the performance by disabling this synchronization. Fourth, we evaluate the improving method and show that the method can significantly improve the writing performance with copy_up by 680 times at most.