1.备份原数据
cd /etc/yum.repos.d/
mkdir bak
mv CentOS-* bak
2.下载新的源文件
wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo
3.建立新的元数据缓存
yum makecache
cd /etc/yum.repos.d/
mkdir bak
mv CentOS-* bak
wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo
yum makecache