1.9 Removing RHCK From a System

If you need to remove RHCK from a system, you can use the kernel-transition package to prepare the system for removing RHCK without removing dependent packages such as bluez, fuse, and irqbalance that might be needed for system operation. The kernel-transition package does not contain any files itself, but instead transfers the package dependencies from the kernel package to the kernel-uek package.

Note

You must have subscribed the system to be transitioned to the ol6_latest channel on ULN.

Because the xorg-x11-drv-nouveau package requires kernel-drm-nouveau version 16, but kernel-uek provides kernel-uek-drm-nouveau version 12, removing the RHCK also removes xorg-x11-drv-nouveau. If you use this procedure on systems with Nvidia graphics hardware, the graphical interface will become low resolution and slow.

Transition a system from the Red Hat Compatible kernel to the Unbreakable Enterprise Kernel as follows:

  1. Install the kernel-transition package on the system:

    # yum install kernel-transition

    This command changes the dependencies for important packages from the RHCK to UEK.

  2. Remove RHCK:

    # yum remove kernel

    This command prompts you before removing remaining packages that depend on RHCK.

    Caution

    When yum prompts you to remove a package, only remove packages that relate to the kernel package. If you are prompted to remove a package that your system requires, enter n to prevent the package being removed. You should also retain any other dependent packages.

    Running the yum update command subsequently updates only UEK.

To reinstall RHCK, run the following command:

# yum install kernel

You can also use kernel-transition with a kickstart installation. Include the following lines in the %packages section to install the kernel-uek and kernel-transition packages, but not the kernel package:

-kernel
kernel-transition

If you create a customized installation ISO, you can replace the kernel package with the kernel-transition package so that dependency resolution pulls in kernel-transition instead of kernel. If kernel-transition is present on the installation media, it cannot be installed accidentally because it provides a kernel version that is lower than that of any RHCK.