安装系统后发现该国产服务器不支持oracle linux uek内核，只得切换到redhat内核。

[root@db1 ~]#  uname -a
Linux db1 5.4.17-2011.6.2.el7uek.x86_64 #2 SMP Thu Sep 3 14:09:14 PDT 2020 x86_64 x86_64 x86_64 GNU/Linux
 
[root@db1 ~]#  awk -F\' '$1=="menuentry " {print i++ " : " $2}' /etc/grub2.cfg
0 : Oracle Linux Server (5.4.17-2011.6.2.el7uek.x86_64 with Unbreakable Enterprise Kernel) 7.9
1 : Oracle Linux Server (3.10.0-1160.el7.x86_64 with Linux) 7.9
2 : Oracle Linux Server (0-rescue-57724e4d2a064aaeabe79777a393dd73 with Linux) 7.9

[root@db1 ~]# grub2-set-default 1

[root@db1 ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
sed: can't read /etc/system-release: No such file or directory

解决方法：
[root@db1 ~]# cp /etc/redhat-release /etc/redhat-release.bak
[root@db1 ~]# mv /etc/redhat-release /etc/oracle-release

解决后再次执行

[root@db1 ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-5.4.17-2102.201.3.el7uek.x86_64
Found initrd image: /boot/initramfs-5.4.17-2102.201.3.el7uek.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-1160.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1160.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-2f30d4e108e947abbe8c295cfc5d8716
Found initrd image: /boot/initramfs-0-rescue-2f30d4e108e947abbe8c295cfc5d8716.img

done
[root@db1 ~]# reboot

重启后查看

[root@db1 ~]# uname -a
Linux db1 3.10.0-1160.el7.x86_64 #1 SMP Thu Oct 1 17:21:35 PDT 2020 x86_64 x86_64 x86_64 GNU/Linux
[root@db1 ~]#