问题描述：

[root@localhost /]# yum -y install centos2anolis AnolisOS-8 - AppStream                                                                                                                                                                        0.0  B/s |   0  B     02:00 Errors during downloading metadata for repository 'AppStream':  - Curl error (28): Timeout was reached for http://mirrors.cloud.aliyuncs.com/anolis/8/AppStream/x86_64/os/repodata/repomd.xml [Connection timed out after 30001 milliseconds]  - Curl error (28): Timeout was reached for http://mirrors.cloud.aliyuncs.com/anolis/8/AppStream/x86_64/os/repodata/repomd.xml [Connection timed out after 30000 milliseconds] 错误：为仓库 'AppStream' 下载元数据失败 : Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried

问题分析：参照《CentOS 8迁移Anolis OS 8手册》 进行到安装迁移工具centos2anolis时报错的，错误信息来看，问题出在无法从指定的镜像源（mirrors.cloud.aliyuncs.com）下载元数据。报错的具体原因是 Connection timed out，意味着请求超时，通常是由于网络连接问题或者该镜像源不可访问。

解决方案：

cp /etc/yum.repos.d/anolis-migration.repo /etc/yum.repos.d/anolis-migration.repo.bak

sudo vi /etc/yum.repos.d/anolis-migration.repo

[migration]

name=Anolis OS - migration repo

baseurl=https://mirrors.tuna.tsinghua.edu.cn/anolis/migration/$releasever/$basearch/os/

gpgcheck=1

gpgkey=https://mirrors.tuna.tsinghua.edu.cn/anolis/RPM-GPG-KEY-ANOLIS

enabled=1

[migration-debug]

name=Anolis OS - migration debug repo

baseurl=https://mirrors.tuna.tsinghua.edu.cn/anolis/migration/$releasever/$basearch/debug/

gpgcheck=1

gpgkey=https://mirrors.tuna.tsinghua.edu.cn/anolis/RPM-GPG-KEY-ANOLIS

enabled=0

[migration-source]

name=Anolis OS - migration source repo

baseurl=https://mirrors.tuna.tsinghua.edu.cn/anolis/migration/$releasever/source/

gpgcheck=1

gpgkey=https://mirrors.tuna.tsinghua.edu.cn/anolis/RPM-GPG-KEY-ANOLIS

enabled=0

sudo yum clean allsudo yum makecache

sudo yum -y install centos2anolis