Optimizing SSD's Performance In The Virtualized Environment

As a new type of storage device, SSD(Solid State Drive) has been widely used in the virtualized environment. However, most existing optimization researches for SSD are oriented to the traditional physical environment, and they are probably not suitable for the virtualized environment. Thus, we need to explore how to maximize SSD's performance in the virtualized environment. In addition, it is important to achieve I/O performance isolation in the enterprise environment, and the traditional solution for this problem is designed for the hard disk drive, which is disagree with SSD, thus it is also of great significance to study how to achieve I/O performance isolation in a virtualized environment using SSD as storage device.SSD's performance can vary a lot with different system configuration parameters in the virtualized environment, thus quantitative evaluations have been done in our work, the parameters covered in our tests are file systems, I/O scheduler algorithms, NCQ(Native Command Queue) depths and virtual machine partition alignment, we give suggestions on how to optimize SSD's performance. For I/O performance isolation, FTBS(Fair Time-share Based on request Size) is introduced to address this problem in the virtualized environment. FTBS is based on the fact that “SSD's I/O time is associated with request's size rather than request's position”. FTBS schedulers request by request's weight and FTBS is also size perceived, which can achieve great performance isolation.The experimental results show that bad system configuration can bring obvious performance degradation(by an average of 40%) of SSD; As for I/O performance isolation, compared with traditional linux scheduling algorithms, FTBS can achieve nearly fair allocation of bandwidth among different virtual machines while the overall average performance loss caused by FTBS is only about 8%.