1. Use the hard disk diagnosis tool to check the health status of the server hard disks. Figure 2 displays the health scores of the hard disks. The red circle marks the health status of the two hard disks used in the RAID 1 array where the OS is installed.
Figure 2 Checking the hard disks
Note: Replace SATA hard disks whose scores are lower than 80.
2. Reinstall the OS. If the OS runs properly, the problem is resolved.
Cause analysis: The health status of the hard disks is abnormal, and the disk partitions may be damaged. In this case, the OS cannot be accessed and “No operating system” is displayed.