In the case of hard drive and SCSI problems, which command should be run?

The command that should be run in the case of hard drive and SCSI problems is "dmesg." This command is used to display the kernel ring buffer messages, which include system log messages that the kernel produces during the boot process and in response to events. When dealing with hard drive or SCSI issues, running dmesg can provide valuable information about hardware detection, errors, device initialization, and other critical events that can inform you about the status and health of your hard drives and SCSI devices.

The output can indicate specific errors related to disk access problems, identify devices that the system is having trouble communicating with, or show if there are configuration issues. This makes it an essential tool for troubleshooting hardware issues in a Linux environment.

In contrast, other choices serve different purposes: fdisk is mainly used for partitioning disks, mount is used to attach file systems to the directory structure, and parted is a tool for manipulating disk partitions. While these commands are useful in specific contexts, they do not provide the troubleshooting information regarding ongoing hardware issues that dmesg does.