真正在意的SE会坚持使用正宗的RHEL，而不会随便切换到CentOS或OEL，即使他们没有Redhat订阅服务。
如果没有商业服务，RHEL8一直会有提示信息：
Updating Subscription Management repositories.
Unable to read consumer identity
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.你可以通过修改vim /etc/yum/pluginconf.d/subscription-manager.conf 中的参数为0去disable订阅提醒。
通常我会建议客户卸载订阅模块儿，而不是将yum切换成CentOS体系：
[root@localhost ~]# yum remove subscription-manager
Dependencies resolved.
==============================================================================================================================
Package Arch Version Repository Size
==============================================================================================================================
Removing:
subscription-manager x86_64 1.23.8-35.el8 @anaconda 4.2 M
Removing dependent packages:
subscription-manager-cockpit noarch 1.23.8-35.el8 @anaconda 3.2 M
subscription-manager-plugin-container x86_64 1.23.8-35.el8 @anaconda 19 k
Removing unused dependencies:
python3-ethtool x86_64 0.14-3.el8 @anaconda 92 k
python3-inotify noarch 0.9.6-13.el8 @anaconda 243 k
python3-subscription-manager-rhsm x86_64 1.23.8-35.el8 @anaconda 369 k
subscription-manager-rhsm-certificates x86_64 1.23.8-35.el8 @anaconda 7.2 k
Transaction Summary
==============================================================================================================================
Remove 7 Packages
Freed space: 8.2 M
Is this ok [y/N]: y
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1
Running scriptlet: subscription-manager-plugin-container-1.23.8-35.el8.x86_64 1/1
Erasing : subscription-manager-plugin-container-1.23.8-35.el8.x86_64 1/7
Erasing : subscription-manager-cockpit-1.23.8-35.el8.noarch 2/7
Running scriptlet: subscription-manager-1.23.8-35.el8.x86_64 3/7
Erasing : subscription-manager-1.23.8-35.el8.x86_64 3/7
warning: /etc/dnf/plugins/subscription-manager.conf saved as /etc/dnf/plugins/subscription-manager.conf.rpmsave
Running scriptlet: subscription-manager-1.23.8-35.el8.x86_64 3/7
Erasing : python3-subscription-manager-rhsm-1.23.8-35.el8.x86_64 4/7
Erasing : subscription-manager-rhsm-certificates-1.23.8-35.el8.x86_64 5/7
Erasing : python3-inotify-0.9.6-13.el8.noarch 6/7
Erasing : python3-ethtool-0.14-3.el8.x86_64 7/7
Running scriptlet: python3-ethtool-0.14-3.el8.x86_64 7/7
Verifying : python3-ethtool-0.14-3.el8.x86_64 1/7
Verifying : python3-inotify-0.9.6-13.el8.noarch 2/7
Verifying : python3-subscription-manager-rhsm-1.23.8-35.el8.x86_64 3/7
Verifying : subscription-manager-1.23.8-35.el8.x86_64 4/7
Verifying : subscription-manager-cockpit-1.23.8-35.el8.noarch 5/7
Verifying : subscription-manager-plugin-container-1.23.8-35.el8.x86_64 6/7
Verifying : subscription-manager-rhsm-certificates-1.23.8-35.el8.x86_64 7/7
Installed products updated.
Removed:
subscription-manager-1.23.8-35.el8.x86_64 subscription-manager-cockpit-1.23.8-35.el8.noarch
subscription-manager-plugin-container-1.23.8-35.el8.x86_64 python3-ethtool-0.14-3.el8.x86_64
python3-inotify-0.9.6-13.el8.noarch python3-subscription-manager-rhsm-1.23.8-35.el8.x86_64
subscription-manager-rhsm-certificates-1.23.8-35.el8.x86_64
Complete!
[root@localhost ~]# cat /etc/yum/pluginconf.d/subscription-manager.conf
cat: /etc/yum/pluginconf.d/subscription-manager.conf: No such file or directory
[root@localhost ~]# 再配合本地RHEL8的yum source使用，这样调整最小而整个OS就安静了！