1. 最小化安装的系统 (minimal install) 缺少 ifconfig 命令，执行 yum install net-tools
2. CentOS Minimal Install Setup:

curl "https://bootstrap.pypa.io/get-pip.py" -o "get-pip.py" python get-pip.py yum install gcc yum install python-devel yum install openssl-devel yum install openldap-devel

1. 升级内核 http://www.cloudibee.com/change-default-boot-kernel-in-linux-grub2/

rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm yum install yum-plugin-fastestmirror yum --enablerepo=elrepo-kernel install kernel-ml grep ^menuentry /boot/grub2/grub.cfg | cut -f 2 -d \' | nl -v 0 grub2-set-default 2

1. Delta RPMs TL;DR: yum install -y deltarpm = https://www.certdepot.net/rhel7-get-started-delta-rpms/ =