A Linux administrator rebooted a server.

The best way to prevent this issue from reoccurring in the future is to create a mount unit and enable it to be started at boot. A mount unit is a systemd unit that defines how and where a filesystem should be mounted. By creating a mount unit for the missing filesystem and enabling it with systemct1 enable, the administrator can ensure that the filesystem will be automatically mounted at boot time, regardless of whether it is listed in /etc/fstab or not. Syncing the mount units will not prevent the issue, as it will only synchronize the state of existing mount units with /etc/fstab, not create new ones. Mounting the filesystem manually will not prevent the issue, as it will only mount the filesystem temporarily, not permanently. Remounting all the missing filesystems will not prevent the issue, as it will only mount the filesystems until the next reboot, not after. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 14: Managing Disk Storage, page 457.