先介绍下 conv 参数 CONVS 的含义: ‘fdatasync’ Synchronize output data just before finishing. This forces a physical write of output data. ‘fsync’ Synchronize output data and metadata just before finishing. This forces a physical write of output data and metadata. 这两个参数的区别就在于是否写入元数据。 再介绍下 oflag 参数 FLAGS 的含义: ‘dsync’ Use synchronized I/O for data. For the output file, this forces a physical write of output data on each write. For the input file, this flag can matter when reading from a remote file that has been written to synchronously by some other process. Metadata (e.g., last-access and last-modified time) is not necessarily synchronized. ‘sync’ Use synchronized I/O for both data and metadata. 这两个参数的区别也在于是否写入元数据。 看完了参数说明,我们再来说说上面的两行命令,这两行命令,都是测试磁盘写入性能的,只不过执行第一个命令时,需要很长的时间(以下测试数据来源于我在 AWS 上的免费 EC2 服务器。OS: RHEL7.3 64位):