操作步骤

1. 进入/etc/yum.repos.d目录中（因为该目录存放着软件仓库的配置文件）

2. 创建一个后缀为.repo的配置文件, 例如yumCentos7.repo

3. yumCentos7.repo配置文件的各个配置项如下

   # 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-$releasever - Base - mirrors.aliyun.com
   failovermethod=priority
   baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/
           http://mirrors.aliyuncs.com/centos/$releasever/os/$basearch/
           http://mirrors.cloud.aliyuncs.com/centos/$releasever/os/$basearch/
   gpgcheck=1
   gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
   
   #released updates 
   [updates]
   name=CentOS-$releasever - Updates - mirrors.aliyun.com
   failovermethod=priority
   baseurl=http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/
           http://mirrors.aliyuncs.com/centos/$releasever/updates/$basearch/
           http://mirrors.cloud.aliyuncs.com/centos/$releasever/updates/$basearch/
   gpgcheck=1
   gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
   
   #additional packages that may be useful
   [extras]
   name=CentOS-$releasever - Extras - mirrors.aliyun.com
   failovermethod=priority
   baseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/
           http://mirrors.aliyuncs.com/centos/$releasever/extras/$basearch/
           http://mirrors.cloud.aliyuncs.com/centos/$releasever/extras/$basearch/
   gpgcheck=1
   gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
   
   #additional packages that extend functionality of existing packages
   [centosplus]
   name=CentOS-$releasever - Plus - mirrors.aliyun.com
   failovermethod=priority
   baseurl=http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/
           http://mirrors.aliyuncs.com/centos/$releasever/centosplus/$basearch/
           http://mirrors.cloud.aliyuncs.com/centos/$releasever/centosplus/$basearch/
   gpgcheck=1
   enabled=0
   gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
   
   #contrib - packages by Centos Users
   [contrib]
   name=CentOS-$releasever - Contrib - mirrors.aliyun.com
   failovermethod=priority
   baseurl=http://mirrors.aliyun.com/centos/$releasever/contrib/$basearch/
           http://mirrors.aliyuncs.com/centos/$releasever/contrib/$basearch/
           http://mirrors.cloud.aliyuncs.com/centos/$releasever/contrib/$basearch/
   gpgcheck=1
   enabled=0
   gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

4. 按配置参数中所填写的仓库位置挂载光盘, 并把光盘挂载信息写入到/etc/fstab文件中