How to boot RHEL 8 into Rescue mode from installation DVD/ISO

As the name implies, rescue mode is provided to rescue your system when the system unable to boot normally into Red Hat Enterprise Linux with runlevel 3 or 5.

You might need to boot RHEL 8 system into rescue mode from installation DVD/ISO for any of the following reasons:

  • To reinstall GRUB2 boot loader on Red Hat Enterprise Linux 8
  • To repair corrupted root partition on Red Hat Enterprise Linux 8
  • The system does not boot into the GRUB menu

What is Anaconda Rescue Mode

The anaconda rescue mode allows user to boot a small Red Hat Enterprise Linux environment entirely from ISO, instead of the system’s hard drive. The rescue mode allows you to access the files stored on your system’s hard drive, even if you cannot actually run Red Hat Enterprise Linux 8 from that hard drive.

It includes many tools for recovering a system, such as all common file system, disk, LVM and networking tools.

Boot a system into Rescue mode from an installation boot medium

Step-1: Boot Red Hat 8 system from an installation source that can be a DVD image, ISO image, or USB drive. We will boot the system with the ISO image as it is easy to mount anywhere like Physical system or Virtual system.

Step-2: Once the system has successfully booted from the ISO image, the boot screen will appear. Select the ‘Troubleshooting’ option and press enter.

Red Hat Enterprise Linux 8 Troubleshooting Menu

Step-3: In the next screen, select the ‘Rescue a Red Hat Linux system’ option and press enter.

Red Hat Enterprise Linux 8 Rescue Mode from Installation DVD/ISO Option

Step-4: When prompted to mount disks on the next screen, select option '1 (Continue)'.

Mount the RHEL 8 root partition under /mnt/sysimage directory using Rescue Mode from installation DVD/ISO

The rescue environment will now attempt to find your Linux installation and mount it under the directory ‘/mnt/sysimage’, but in read-only mode.

RHEL 8 Rescue Mode is mounted your root partition under /mnt/sysimage directory

Step-5: Press 'Enter' to obtain a shell when prompted. This shell will live inside the installation/rescue environment, but the actual system mounted under /mnt/sysimage.

To obtain a shell on the Rescue Mode using RHEL 8 installation DVD/ISO

Step-6: Chroot into the /mnt/sysimage directory in order to use root partition of original file system instead of Anaconda rescue mode environment root partition.

chroot /mnt/sysimage
Mount actual root partition in the Rescue Mode using the chroot command

Step-7: Once done the troubleshooting, type ‘exit’ twice to boot the system in normal mode.


Wrapping Up

In this guide, we have explained how to boot Red Hat (RHEL) 8 system into Anaconda Rescue Mode from installation DVD/ISO. This same procedure works on other RHEL clones such as CentOS 8, Rocky Linux 8 and AlmaLinux 8.

If you have any questions or feedback, feel free to comment below.

About Magesh Maruthamuthu

Love to play with all Linux distribution

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