Centos7系统安装yum遇到的问题failure: repodata/repomd.xml from base: [Errno 256] No more mirrors to try. http:

当遇到这个问题的时候，发现网上也有很人也在问同样的问题。但是发现大家大都问，很少有人能说的很清楚，而且很多人的解决方法复杂且不能解决问题。我查了近二十篇文章，对照做了，但是基本解决不了问题。

下面由我给出一种最简单最有效的方法。耐心看下去哦！

问题所在：

[root@cit-server6-s1-372 yum.repos.d]# yum makecache
Loaded plugins: fastestmirror
base                                                                     | 5.6 kB  00:00:00     
http://mirrors.163.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno -1] Error importing repomd.xml for base: Damaged repomd.xml file
Trying other mirror.


 One of the configured repositories failed (CentOS-7 - Base - 163.com),
 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. Disable the repository, 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 base

     4. 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=base.skip_if_unavailable=true

failure: repodata/repomd.xml from base: [Errno 256] No more mirrors to try.
http://mirrors.163.com/centos/7/os/x86_64/repodata/repomd.xml: [Errno -1] Error importing repomd.xml for base: Damaged repomd.xml file
[root@cit-server6-s1-372 yum.repos.d]# 

错误所在的问题：

主要问题在于yum源问题。

下面开始解决问题：

下面这一段参考博客：https://blog.csdn.net/shaoqiufeng/article/details/78785806

1. 查看centos7.2系统本身所安装的yum依赖包

[root@zf-test-web01-4 ~]# rpm -qa|grep yum
yum-plugin-fastestmirror-1.1.31-34.el7.noarch
yum-metadata-parser-1.1.4-10.el7.x86_64

yum-3.4.3-132.el7.centos.0.1.noarch

2. 卸载这些软件包

[root@zf-test-web01-4 ~]# rpm -e yum-plugin-fastestmirror-1.1.31-34.el7.noarch --nodeps
warning: /etc/yum/pluginconf.d/fastestmirror.conf saved as /etc/yum/pluginconf.d/fastestmirror.conf.rpmsave
[root@zf-test-web01-4 ~]# rpm -e yum-metadata-parser-1.1.4-10.el7.x86_64 --nodeps
[root@zf-test-web01-4 ~]# rpm -e yum-3.4.3-132.el7.centos.0.1.noarch --nodeps
[root@zf-test-web01-4 ~]# 

3. 进入centos镜像网站找到自己对应系统需要的yum包

    查看系统的命令：

[root@zf-test-web01-4 ~]# cat /etc/redhat-release
CentOS Linux release 7.2.1511 (Core) 

   查看系统的位数：

[root@zf-test-web01-4 ~]# file /bin/ls
/bin/ls: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.32, BuildID[sha1]=aa7ff68f13de25936a098016243ce57c3c982e06, stripped

4.下载并安装yum依赖包

wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-34.el7.noarch.rpm
wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/yum-3.4.3-132.el7.centos.0.1.noarch.rpm

5. 安装下载的这些yum包
[root@zf-test-web01-4 ~]# rpm -ivh yum-*
Preparing...                          ################################# [100%]
Updating / installing...
   1:yum-metadata-parser-1.1.4-10.el7 ################################# [ 33%]
   2:yum-plugin-fastestmirror-1.1.31-3################################# [ 67%]
   3:yum-3.4.3-132.el7.centos.0.1     ################################# [100%]

[root@zf-test-web01-4 ~]
6. 更新centos系统的repo文件
http://mirrors.163.com/.help/centos.html
1）首先备份/etc/yum.repos.d/CentOS-Base.repo
[root@zf-test-web01-4 yum.repos.d]# mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
2）下载对应版本repo文件, 放入/etc/yum.repos.d/(操作前请做好相应备份)
3）运行以下命令生成缓存
[root@zf-test-web01-4 yum.repos.d]# yum clean all
Loaded plugins: fastestmirror
Repodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast
Cleaning repos: base extras updates
Cleaning up everything
Cleaning up list of fastest mirrors
[root@zf-test-web01-4 yum.repos.d]# yum makecache
Loaded plugins: fastestmirror
base                                                             | 3.6 kB  00:00:00     
extras                                                           | 3.4 kB  00:00:00     
updates                                                          | 3.4 kB  00:00:00     
(1/12): base/7/x86_64/group_gz                                   | 156 kB  00:00:00     
(2/12): base/7/x86_64/filelists_db                               | 6.7 MB  00:00:01     
(3/12): extras/7/x86_64/prestodelta                              |  71 kB  00:00:00     
(4/12): extras/7/x86_64/primary_db                               | 145 kB  00:00:00     
(5/12): extras/7/x86_64/filelists_db                             | 528 kB  00:00:00     
(6/12): extras/7/x86_64/other_db                                 |  97 kB  00:00:00     
(7/12): updates/7/x86_64/prestodelta                             | 589 kB  00:00:00     
(8/12): base/7/x86_64/primary_db                                 | 5.7 MB  00:00:01     
(9/12): base/7/x86_64/other_db                                   | 2.5 MB  00:00:00     
(10/12): updates/7/x86_64/primary_db                             | 4.5 MB  00:00:00     
(11/12): updates/7/x86_64/other_db                               | 490 kB  00:00:00     
(12/12): updates/7/x86_64/filelists_db                           | 2.7 MB  00:00:01     
Determining fastest mirrors
Metadata Cache Created
7. 重新运用yum安装软件