報錯資訊：404 Not Found

Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
* base: mirrors.aliyun.com
* extras: mirrors.aliyun.com
* updates: mirrors.aliyun.com
http://mirrors.aliyun.com/centos/6.9/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found"
Trying other mirror.
To address this issue please refer to the below knowledge base article

https://access.redhat.com/articles/1320623

If above article doesn't help to resolve this issue please open a ticket with Red Hat Support.

http://mirrors.aliyuncs.com/centos/6.9/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 7 - "couldn't connect to host"
Trying other mirror.
http://mirrors.cloud.aliyuncs.com/centos/6.9/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - "Couldn't resolve host 'mirrors.cloud.aliyuncs.com'"
Trying other mirror.
Error: Cannot retrieve repository metadata (repomd.xml) for repository: base. Please verify its path and try again

解決程序

報錯資訊404：說明http://mirrors.aliyun.com/centos/6.9/os/x86_64/repodata/repomd.xml 這個資源不存在！！！

思路：在瀏覽器上手動打開 http://mirrors.aliyun.com/centos/6.9

打開readme檔案資訊如下：

發現支持6.9的鏡像資源

解決問題

以下操作都在root權限下：

cd /etc/yum.repos.d

cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak 保留一份系統自帶yum源檔案

vi /etc/yum.repos.d/CentOS-Base.repo

給出修改好的CentOS-Base.repo

# 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-6.9 - Base
#mirrorlist=http://mirrorlist.centos.org/?release=6.9&arch=$basearch&repo=os&infra=$infra
baseurl=http://mirror.nsc.liu.se/centos-store/6.9/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#released updates 
[updates]
name=CentOS-6.9 - Updates
#mirrorlist=http://mirrorlist.centos.org/?release=6.9&arch=$basearch&repo=updates&infra=$infra
baseurl=http://mirror.nsc.liu.se/centos-store/6.9/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#additional packages that may be useful
[extras]
name=CentOS-6.9 - Extras
#mirrorlist=http://mirrorlist.centos.org/?release=6.9&arch=$basearch&repo=extras&infra=$infra
baseurl=http://mirror.nsc.liu.se/centos-store/6.9/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-6.9 - Plus
#mirrorlist=http://mirrorlist.centos.org/?release=6.9&arch=$basearch&repo=centosplus&infra=$infra
baseurl=http://mirror.nsc.liu.se/centos-store/6.9/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#contrib - packages by Centos Users
[contrib]
name=CentOS-6.9 - Contrib
#mirrorlist=http://mirrorlist.centos.org/?release=6.9&arch=$basearch&repo=contrib&infra=$infra
baseurl=http://mirror.nsc.liu.se/centos-store/6.9/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

接下來，基本操作

yum clean all

yum makecache 下載較慢，請耐性等待

總結

https://vault.centos.org/ 下面有CentOS不再支持的版本資源，缺點就是太慢了，得等

盡量用官方支持的版本，CentOS7.0及以上，排查問題會快很多，或者根本不會出現問題，

等個錘子！！！

睡了睡了