设置yum源为阿里云
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
添加epel源
wget -P /etc/yum.repos.d/ http://mirrors.aliyun.com/repo/epel-7.repo
清理缓存并生成新的缓存
yum clean all
yum makecache
原文：http://blog.51cto.com/13491150/2059198