1. Are you expert in this kind of job?
2. Following tutorials seem simple but is it possible to add a system that check everything is working? Sometimes doing also real tests to be sure.
3. Is there any other things to add into the system?
4. the second server, can be a simple LAMP with centos or is it better to have cpanel installed also in it, if i need to transfer new accounts?
1. Yes, I have done several failover setups.
2. Adding system checks is always possible, took at crontab, anacrontab, on systemd init.
3. I think you covered it pretty nice, but I would like to tell you can CPanel is sh*it because it makes deep changes to your CentOS, so much that CentOS user forum/channels won't help you because you use CPanel. It also adds overhead.
4. LAMP will be fine, you can transfer accounts with other means that CPanel, really.
But if you're sync'ing servers that are different, better have the same setup on both.
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Kind regards,