Scope/Description

How to repair a CentOS installation that is stuck booting into GRUB.

Prerequisites

• A unit that is unable to properly boot into CentOS
• Access to the IPMI management port on the 45 Drives unit
• Java installed for ISO mounting
• ISO for the matching version of CentOS 7 downloaded

Steps

• Open the Java IPMI management tool from the IPMI web GUI

• Click “Virtual Media”, followed by “Virtual Storage”.

• Select the drive type. In this case, ISO, and navigate to the file

• Click “Plug In” then “OK”

• Reboot the unit using “Power Control” and “Set Power Reset”. When the unit is reboot, hammer the F11 key until the boot menu appears.

• Select ATEN Virtual CDROM YSOJ

• Select Troubleshooting, then Rescue a CentOS System

• This will boot the unit into Anaconda Recovery mode. From here, we can repair the OS installation.

• Enter 1 to continue

• Press enter to engage the shell, then input “chroot /mnt/sysimage” to enter bash.

• From here, we can use lsblk to identify which drives are being used as our boot drives. In this case, it’s sda and sdb

• Next step is to re-write the MBR of the boot devices using grub2install. If you have redundant boot drives, you will have to repeat this step for both devices.

• Navigate to /boot/grub2 and check the directory. Grub.cfg should be present.
  

• From here, we’ll need to generate a new grub.cfg file using the following command:
  grub2-mkconfig -o /boot/grub2/grub.cfg

• Exit from chroot and reboot the system using init 6 in the shell.

Verification

• Boot into the OS and ensure it will properly post.