Cloud Server ECS Linux CentOS modify kernel boot sequence

CentOS 7.0 System changes kernel boot order

Since CentOS 7 uses GRUB2 as the boot program, it differs from CentOS 6 and does not modify the/etc/grub.conf to modify the startup item, which requires the following actions:

1. Look at the number of cores inside the system:

1. cat /boot/grub2/grub.cfg |grep menuentry

2.. Configure boot from the default kernel, the kernel name of the following command is replaced by the actual name found inside the system:

1. grub2-set-default “CentOS Linux (3.10.0-123.9.3.el7.x86_64) 7 (Core)”

3. Verify that the configuration is successful:

1. grub2-editenv list

CentOS 6.X System changes kernel boot order

Open/etc/grub.conf to view the system kernel, the following is the phenomenon of the system has multiple cores:

To modify the configuration steps:

1. From being able to see that there are already two kernel versions, from the top down the kernel version is 2.6.32-573.18.1.el6.x86_64 and 2.6.32-431.23.3.el6.x86_64 in turn.
2. In the grub.conf file, decide which kernel version to use to boot the parameter is default, defaults to 0 (representing the boot from the latest kernel, the kernel version represented from the top down is 0, 1, 2, etc.).
3. In this example, if you want to boot from the old kernel, the system's first kernel, change the default value to 1, and then reboot the server to boot from the new kernel.

Cloud Server ECS Linux CentOS modify kernel boot sequence