Arch offers its updates on a rolling release schedule. Arch linux is updated to the newest version with the command:
pacman -Syu
Arch linux will overwrite the kernel when the upstream maintainers release a new kernel package. In many instances, especially in a virtualized environment, where the kernel might be located outside of the running server, it is necessary to tell pacman to ignore upgrading the linux kernel.
To do so, add this line to the pacman configuration file, /etc/pacman.conf:
IgnorePkg = linux
Once this line is modified, any future updates to the system will skip the kernel overwrite.