We have an RHEL 7.5 server with latest updates. We installed Oracle 12 DB on it by choosing the "easy method" of installing "oracle-database-server-12cR2-preinstall-1.0-3.el7.x86_64.rpm". Everything went smooth and all OK but later we noticed that it has Oracle Kernel ver 4.14 uek installed instead of using Redhat's 3.10 ver. and using updates from Oracle Yum. we need to switch the kernel back to Redhat's by keeping all the software (esp Oracle) intact.
We can see both Oracle kernel entries & Redhat entries in grub.conf but not sure If I can simply boot Redhat 3.x kernel with oracle too working fine.
title Oracle Linux Server 7.5, with Linux 3.10.0-862.11.6.el7.x86_64
root (hd0,0)
kernel /vmlinuz-3.10.0-862.11.6.el7.x86_64 root=/dev/mapper/SystemVG-rootLV ro rd.lvm.lv=SystemVG/swapLV rd.luks=0 KEYBOARDTYPE=pc vconsole.keymap=uk rd.locale.LANG=en_GB.UTF-8 rd.md=0 rd.lvm.lv=SystemVG/rootLV vconsole.font=latarcyrheb-sun16 crashkernel=auto rd.dm=0 rhgb quiet rhgb quiet LANG=en_GB.UTF-8
initrd /initramfs-3.10.0-862.11.6.el7.x86_64.img
title Oracle Linux Server 7.5, with Unbreakable Enterprise Kernel 4.14.35-1818.0.9.el7uek.x86_64
root (hd0,0)
kernel /vmlinuz-4.14.35-1818.0.9.el7uek.x86_64 root=/dev/mapper/SystemVG-rootLV ro rd.lvm.lv=SystemVG/swapLV rd.luks=0 KEYBOARDTYPE=pc vconsole.keymap=uk rd.locale.LANG=en_GB.UTF-8 rd.md=0 rd.lvm.lv=SystemVG/rootLV vconsole.font=latarcyrheb-sun16 crashkernel=auto rd.dm=0 rhgb quiet rhgb quiet LANG=en_GB.UTF-8
initrd /initramfs-4.14.35-1818.0.9.el7uek.x86_64.img
title Red Hat Enterprise Linux Server (3.10.0-862.9.1.el7.x86_64) 7.5 (Maipo)
root (hd0,0)
kernel /vmlinuz-3.10.0-862.9.1.el7.x86_64 root=/dev/mapper/SystemVG-rootLV ro rd.lvm.lv=SystemVG/swapLV rd.luks=0 KEYBOARDTYPE=pc vconsole.keymap=uk rd.locale.LANG=en_GB.UTF-8 rd.md=0 rd.lvm.lv=SystemVG/rootLV vconsole.font=latarcyrheb-sun16 crashkernel=auto rd.dm=0 rhgb quiet rhgb quiet LANG=en_GB.UTF-8
initrd /initramfs-3.10.0-862.9.1.el7.x86_64.img
title Red Hat Enterprise Linux Server 7.5 Rescue d2d830879078ddddf4d061d50000001f (3.10.0-862.el7.x86_64)
root (hd0,0)
kernel /vmlinuz-0-rescue-d2d830879078ddddf4d061d50000001f root=/dev/mapper/SystemVG-rootLV ro rd.lvm.lv=SystemVG/swapLV rd.luks=0 KEYBOARDTYPE=pc vconsole.keymap=uk rd.locale.LANG=en_GB.UTF-8 rd.md=0 rd.lvm.lv=SystemVG/rootLV vconsole.font=latarcyrheb-sun16 crashkernel=auto rd.dm=0 rhgb quiet rhgb quiet LANG=en_GB.UTF-8
initrd /initramfs-0-rescue-d2d830879078ddddf4d061d50000001f.img
title Red Hat Enterprise Linux Server (3.10.0-862.el7.x86_64) 7.5 (Maipo)
root (hd0,0)
kernel /vmlinuz-3.10.0-862.el7.x86_64 root=/dev/mapper/SystemVG-rootLV ro rd.lvm.lv=SystemVG/swapLV rd.luks=0 KEYBOARDTYPE=pc vconsole.keymap=uk rd.locale.LANG=en_GB.UTF-8 rd.md=0 rd.lvm.lv=SystemVG/rootLV vconsole.font=latarcyrheb-sun16 crashkernel=auto rd.dm=0 rhgb quiet rhgb quiet LANG=en_GB.UTF-8
initrd /initramfs-3.10.0-862.el7.x86_64.img
[root@lnxoraprod02 ~]# uname -a
Linux lnxoraprod02 4.14.35-1818.0.9.el7uek.x86_64 #2 SMP Mon Jun 18 20:32:24 PDT 2018 x86_64 x86_64 x86_64 GNU/Linux
[root@lnxoraprod02 ~]#
As per our company policy, all machines must be supported by Redhat only and Oracle DB to be supported by Oracle. Could anyone please advise on how to switch back to RH kernel without breaking anything? I know rebuilding the server from scratch and not choosing "preinstall rpm" method will fix that but that's a too long process.