Clustered file system is a key component of cloud computing. It can be divided into two major groups, which are shared-disk file system and distributed file system, in which the latter is the hot spot of academic research in recent years. This paper mainly focuses on IOPS, which is an important performance indicator for VM(virtual machine). We employ fio as the testing tool and experimental results show that,(1) when a VM runs on sharing-disk file system and distributed cluster file system both with 3 storage nodes, the write IOPS of the former is higher than the latter about 40%, but the read IOPS of latter is 1.5 times as much as the former;(2) when multiple VMs run simultaneously on sharing-disk file system and distributed cluster file system both with less than 16 storage nodes, the write IOPS of VMs for both clusters are almost the same; otherwise, the write IOPS performance of the latter is better than the former.