Just start with a raspberry pie 4B 3B replace the old ride Nas. Tucao card and USB 3B speed is really slow.
While the official recommendation is Debian, CentOS do not want to get used to due to the increase in the cost of learning, I decided to use CentOS.
Mirror Download: http://mirrors.huaweicloud.com/centos-altarch/7.6.1810/isos/armhfp/
With balenaEtcher burn it to TF card, but can not start on 4B.
Under confirm the current CentOS does not support Raspberry Pi mirror 4B. Reference: https://www.centos.org/forums/viewtopic.php?p=300505
But the method has to solve, it is to update the kernel.
Step one, 2 or 3 Raspberry Pi find, insert the TF card. Power Update
yum update -y
Step two, download the kernel update package
Download: https://buildlogs.centos.org/c7-exp.armhfp/raspberrypi2/20190729164752/4.19.61-v7l.1.el7.armhfp/
Download rpm package
yum localinstall
Step three, off the TF card to change 4B, the magic happened. Start successfully.