使用yum的官方源进行yum install xxxx 的时候，速度非常慢，只有几kB/s，有时候还不到1kB/s。这就会造成安装包的速度的速度要么特变慢，要么就根本安装不了。如下图所示。
 

 
解决方案：
替换CentOS的yum 源 为 国内的镜像源。以下方法适用余centos6.*和centos7.*
 
更换 yum 源的原因：
国外网站连接响应太慢
国内 yum 源响应速度快
 
解决方案1：替换CentOS的yum 源 为 国内的yum源--阿里yum源。
 
具体步骤如下：
1.备份
 
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
 
2.下载新的 CentOS-Base.repo 到 /etc/yum.repos.d/
 
CentOS6
 
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
CentOS7
 
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
如下图所示：

 
3.之后运行yum makecache生成缓存
 
yum makecache
 
这一步还是比较耗时的，而且速度不快几k到几十k每秒之间，可以不执行
最终效果
 
最终效果如图，yum源更换为国内阿里镜像源后，yum 安装或更新包的速度非常快，保持在 几MB/s
 

 
有时候用阿里的yum源，会出现问题，“Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error”
 


 
此时，阿里云 yum 源域名无法解析，那么我们就要考虑将阿里yum源换成别的源，比如清华yum源。
 
-----------------------------------------------
 
解决方案2：替换CentOS的yum 源 为 国内的yum源--清华yum源。
 
具体步骤如下：
1.备份
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
 
2.创建 /etc/yum.repos.d/
 
touch /etc/yum.repos.d/CentOS-Base.repo
 
3.向 /etc/yum.repos.d/CentOS-Base.repo 写入 清华大学yum源配置：
 
# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#
 
[base]
name=CentOS-$releasever - Base
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/os/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
 
#released updates
[updates]
name=CentOS-$releasever - Updates
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/updates/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
 
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/extras/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
 
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/centosplus/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
gpgcheck=1
enabled=0
 
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
 
4.结束。接下来可以直接使用yum 安装 所需工具包。