文章轉載自：https://blog.csdn.net/inslow/article/details/54177191
有時候CentOS默認的yum源不一定是國內鏡像，導致yum在線安裝及更新速度不是很理想。這時候需要將yum源設置為國內鏡像站點。國內主要開源的開源鏡像站點應該是網易和阿里雲了。
修改CentOS默認yum源為mirrors.163.com
1、首先備份系統自帶yum源配置文件/etc/yum.repos.d/CentOS-Base.repo
[root@localhost ~]# mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
2、進入yum源配置文件所在的文件夾
[root@localhost ~]# cd /etc/yum.repos.d/
3、下載163的yum源配置文件到上面那個文件夾內
CentOS7
[root@localhost yum.repos.d]# wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
CentOS6
[root@localhost yum.repos.d]# wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
CentOS5
[root@localhost yum.repos.d]# wget http://mirrors.163.com/.help/CentOS5-Base-163.repo
4、運行yum makecache生成緩存
[root@localhost yum.repos.d]# yum makecache
5、這時候再更新系統就會看到以下mirrors.163.com信息
[root@localhost yum.repos.d]# yum -y update
已加載插件：fastestmirror, refresh-packagekit, security
設置更新進程Loading mirror speeds from cached hostfile
* base: mirrors.163.com
* extras: mirrors.163.com
* updates: mirrors.163.com
修改CentOS默認yum源為mirrors.aliyun.com
1、首先備份系統自帶yum源配置文件/etc/yum.repos.d/CentOS-Base.repo
[root@localhost ~]# mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
2、下載ailiyun的yum源配置文件到/etc/yum.repos.d/
CentOS7
[root@localhost ~]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
CentOS6
[root@localhost ~]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
CentOS5
[root@localhost ~]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo
3、運行yum makecache生成緩存
[root@localhost ~]# yum makecache
4、這時候再更新系統就會看到以下mirrors.aliyun.com信息
[root@localhost ~]# yum -y update
已加載插件：fastestmirror, refresh-packagekit, security
設置更新進程Loading mirror speeds from cached hostfile
* base: mirrors.aliyun.com
* extras: mirrors.aliyun.com
* updates: mirrors.aliyun.com