【排错】运行yum命令报错 repodata/repomd.xml from mysql: [Errno 256] No more mirrors to try.的解决方式

[root@localhost ~]# yum -y install httpd php php-mysqlnd php-gd mysql-community-server
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.ustc.edu.cn
 * extras: mirrors.aliyun.com
 * updates: mirrors.ustc.edu.cn
epel                                                                                           | 4.7 kB  00:00:00
https://mirrors.tuna.tsinghua.edu.cn/mysql/yum/mysql-5.6-community-el7-x86_64/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found
正在尝试其它镜像。
To address this issue please refer to the below wiki article

https://wiki.centos.org/yum-errors

If above article doesn't help to resolve this issue please use https://bugs.centos.org/.

 One of the configured repositories failed (mysql5.6),
 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=mysql ...

     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 mysql
        or
            subscription-manager repos --disable=mysql

     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=mysql.skip_if_unavailable=true

failure: repodata/repomd.xml from mysql: [Errno 256] No more mirrors to try.
https://mirrors.tuna.tsinghua.edu.cn/mysql/yum/mysql-5.6-community-el7-x86_64/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found

从这个错误应该可以看出来，应该是有一个源是错误的，因为有的网页打不开，报404错误。

我试着打开红色的网址

 

果然，我们申请的源不存在，清华的源没有5.6版本的MySQL。按照上面的提示，去找镜像 

5.6不能用就用5.7的，复制一下网址，放到mysql.repo中，再安装，成功了。

读懂yum命令输出的错误也是一个方面。