最近在虚拟机下面安装了个CentOS 5.5，使用yum更新时发现下载速度异常慢。可以修改yum的配置文件，把其镜像指向国内的服务器即可。
方案一：
# cd /etc/yum.repos.d/
# mv CentOS-Base.repo CentOS-Base.repo.bak # wget http://docs.linuxtone.org/soft/lemp/CentOS-Base.repo方案二：
手段修改CentOS-Base.repo文件，将baseurl设置成baseurl=http://ftp.sjtu.edu.cn/centos/5/addons/$basearch/ 详细配置如下：[base]
name=CentOS-5-Base #mirrorlist=http://mirrorlist.centos.org/?release=$releasever5&arch=$basearch&repo=os #baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/ baseurl=http://ftp.sjtu.edu.cn/centos/5/os/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5 #released updates [update] name=CentOS-5-Updates #mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=updates baseurl=http://ftp.sjtu.edu.cn/centos/5/updates/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5 #packages used/produced in the build but not released [addons] name=CentOS-5-Addons #mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=addons baseurl=http://ftp.sjtu.edu.cn/centos/5/addons/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5 #additional packages that may be useful [extras] name=CentOS-5-Extras #mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=extras baseurl=http://ftp.sjtu.edu.cn/centos/5/extras/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5 #additional packages that extend functionality of existing packages [centosplus] name=CentOS-5-Plus #mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=centosplus baseurl=http://ftp.sjtu.edu.cn/centos/5/centosplus/$basearch/ gpgcheck=1 enabled=0 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5 #contrib – packages by Centos Users [contrib] name=CentOS-5-Contrib #mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=contrib baseurl=http://ftp.sjtu.edu.cn/centos/5/contrib/$basearch/ gpgcheck=1 enabled=0 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5 导入 key ＃ rpm –import http://ftp.sjtu.edu.cn/centos/5/os/i386/RPM-GPG-KEY-CentOS-5 运行，测试 ＃ yum update 全部删除临时文件 #yum clean all