https://www.jianshu.com/p/4d5e5360c55b

安装阿里云yum源

1、备份
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
2、下载新的CentOS-Base.repo 到/etc/yum.repos.d/
CentOS 5
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo
CentOS 6
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
CentOS 7
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
3、之后运行yum makecache生成缓存
yum clean all
yum makecache

 

阿里云ESC云主机centos6系统yum更新时，会遇到类似如下404等错误：

http://mirrors.aliyun.com/centos/6/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found" Trying other mirror.
http://mirrors.aliyuncs.com/centos/6/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 7 - "couldn't connect to host" Trying other mirror.
Error: Cannot retrieve repository metadata (repomd.xml) for repository: base. Please verify its path and try again

处理方法：修改/etc/yum.repos.d/目录下的CentOS-Base.repo、epel.repo文件

把CentOS-Base.repo文件中的以下网址
http://mirrors.aliyun.com/centos/
http://mirrors.aliyuncs.com/centos/
http://mirrors.cloud.aliyuncs.com/centos/
修改成
http://mirrors.aliyun.com/centos-vault/centos/
 
把epel.repo文件中的
enabled=1
修改成
enabled=0