Cannot find a valid baseurl for repo: centos-sclo-rh

[root@hadoop1 redis-6.0.10]# sudo yum install devtoolset-7-gcc*
已加载插件：fastestmirror, refresh-packagekit, security
设置安装进程
Loading mirror speeds from cached hostfile
Could not retrieve mirrorlist http://mirrorlist.centos.org?arch=x86_64&release=6&repo=sclo-rh error was
12: Timeout on http://mirrorlist.centos.org?arch=x86_64&release=6&repo=sclo-rh: (28, 'Operation too slow. Less than 1 bytes/sec transfered the last 30 seconds')
错误：Cannot find a valid baseurl for repo: centos-sclo-rh

原因:
2020年12月2日官方结束了对CentOS 6.x的支持，导致在使用yum安装或更新程序的时候出现404错误

解决办法:
清空CentOS-Base.repo文件

echo > /etc/yum.repos.d/CentOS-Base.repo

打开CentOS-Base.repo文件并且拷贝下面的内容填入

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

拷贝下面的内容:

[base]
name=CentOS-$releasever - Base
# mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
# baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
baseurl=https://vault.centos.org/6.10/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

# released updates
[updates]
name=CentOS-$releasever - Updates
# mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates&infra=$infra
# baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
baseurl=https://vault.centos.org/6.10/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

# additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
# mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
# baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
baseurl=https://vault.centos.org/6.10/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

删除/etc/yum.repos.d/目录下其他无关的repo文件 [只留下CentOS-Base.repo即可]

cd /etc/yum.repos.d/
ls | grep -v 'CentOS-Base.repo' | xargs rm

重建yum缓存, 更新并启用新的yum源

yum clean all && yum makecache fast