RHEL7 用U盘安装，出现问题，求大神指导

提示信息:
dracut-initqueue[592]:Warning:Could not boot;
dracut-initqueue[592]:Warning:/dev/root does not exist
Starting Dracut Emergency Shell ...
Warning : /dev/root does not exist

Generating "/run/initramfs/rdsosreport.txt"
.............