为什么我在使用yum安装httpd中会报错呢？

帮我分析一下究竟出了什么问题
前面的步骤补充
1、mv /etc/yum.repos.d/* /tmp/ 删除官方yum库
2、vim /etc/yum.repos.d/dvd.repo 自己配置yum库
dvd.reo文件的内容如下
[dvd]
name=dvd
baseurl=file:(3个斜杆"/"，因为发文章的时候不可以重复输入同样的词汇或者符号)mnt/
gpgcheck=0
3、mount /dev/cdrom /mnt/cdrom 将光盘挂载到/mnt/cdrom/

以下是出问题的地方
[root@localhost ~]# ls /mnt/cdrom/
CentOS_BuildTag GPL LiveOS RPM-GPG-KEY-CentOS-7
EFI images Packages RPM-GPG-KEY-CentOS-Testing-7
EULA isolinux repodata TRANS.TBL
[root@localhost ~]# yum -y install httpd
已加载插件：fastestmirror, langpacks
Loading mirror speeds from cached hostfile
file:(3个斜杆"/"，因为发文章的时候不可以重复输入同样的词汇或者符号)mnt/repodata/repomd.xml: [Errno 14] curl#37 - "Couldn't open file /mnt/repodata/repomd.xml"
正在尝试其它镜像。

One of the configured repositories failed (dvd),
and yum doesn't have enough cached data to continue. At this point the only
safe thing yum can do is fail. There are a few ways to work "fix" this:

 1. Contact the upstream for the repository and get them to fix the problem.

 2. Reconfigure the baseurl/etc. for the repository, to point to a working
    upstream. This is most often useful if you are using a newer
    distribution release than is supported by the repository (and the
    packages for the previous distribution release still work).

 3. Run the command with the repository temporarily disabled
        yum --disablerepo=dvd ...

 4. Disable the repository permanently, so yum won't use it by default. Yum
    will then just ignore the repository until you permanently enable it
    again or use --enablerepo for temporary usage:

        yum-config-manager --disable dvd
    or
        subscription-manager repos --disable=dvd

 5. Configure the failing repository to be skipped, if it is unavailable.
    Note that yum will try to contact the repo. when it runs most commands,
    so will have to try and fail each time (and thus. yum will be be much
    slower). If it is a very temporary problem though, this is often a nice
    compromise:

        yum-config-manager --save --setopt=dvd.skip_if_unavailable=true

failure: repodata/repomd.xml from dvd: [Errno 256] No more mirrors to try.
file:(3个斜杆"/"，因为发文章的时候不可以重复输入同样的词汇或者符号)mnt/repodata/repomd.xml: [Errno 14] curl#37 - "Couldn't open file /mnt/repodata/repomd.xml"
[root@localhost ~]#