Some of our clients contacted us recently about the boot problem of their server after installing CloudLinux and it's the kernel. So, here's we're writing a tutorial to fix the boot problem.
First of all, check the version of the kernel installed on your server:
grubby --default-kernel
If no CLN kernel detected, then install grab2:
yum install grub2 --disableexcludes=all
Then re-install the latest CLN kernel and check the kernel version.
If you've already installed CLN kernel, then, re-install the latest kernel of CLN:
yum reinstall kernel-3.10.0-962.3.2.lve1.5.35.el7.x86_64
Now, try to boot with CloudLinux kernel
CloudLinux 7 brings GRUB2 with the totally new scheme of booting the kernels, the old edit file is not applicable anymore. The correct way to boot needed kernel (use an older kernel, CentOS kernel one or debug kernel) is with grub2-set-default command.
1. Take a needed kernel with :
awk -F\' '$1=="menuentry " {print i++ " = "$2}' /etc/grub2.cfg
0 = CloudLinux (3.10.0-427.18.2.lve1.4.27.el7.x86_64) 7.3 (Yury Malyshev) 1 = CloudLinux (3.10.0-427.36.1.lve1.4.26.el7.x86_64) 7.3 (Yury Malyshev) 2 = CloudLinux (3.10.0-427.18.2.lve1.4.24.el7.x86_64) 7.2 (Valeri Kubasov) 3 = CloudLinux (0-rescue-1d7e5b9aa3bd48e99e108700e5458d82) 7.2 (Valeri Kubasov)
Note that the position of a menu entry in the list is denoted by a number starting with zero, so we are numbering it especially in a correct way.
2. Set to boot needed kernel with the command line:
grub2-set-default 1
Use the following command to check currently selected kernel to be booted:
grub2-editenv list
saved_entry=1
Done! Now reboot your server.
