Diagnose & troubleshoot system start up issues-EX342

  • Identify and resolve service failures affecting boot

to find service dependencies you can view the service systemd file at


  1. check the configs file

systemctl status -l vsftpd

2. check all configurations related to a service

3. List dependencies

sysemctl list-dependencies rsyslog

  • Regain root control of a system

You will have to modify the kernel line during boot time as follows:

Press e to edit the selected grub boot line

Add rd.break to the end of the  line that has linux16 then press CTRL+X to boot the system with the grub information entered

Mount the file system

#mount -o remount,rw /sysroot

#chroot /sysroot

Change the root password


Update the selinux labels

#touch /.autorelabel

Restart the system

  • Troubleshoot boot issues

This is dependent of the type of bios that the system is running. You will need to identify  what type of BIOS this system is running.


If the configuration files are missing run the following commands

#grub2-mkconfig -o /boot/grub2/grub.cfg

or reinstall it on a chroot environment on the right disk


#grub2-mkconfig -o /boot/efi/UEFI/redhat/grub.cfg

  • Identify hardware and hardware problems

There are different commands that can be used to identify the hardware running on the system

To get the CPU information


# dmidecode

To get DISK information


To get ISCSI disk information

# lsscsi

To get PCI devices


To see all the options for each command run the man command.

  • Manage kernel modules and their parameters