My problem is a little specific.
I am using 10 core / SSD VPS at Contabo with cPanel and CloudLinux.
I have ~80 accounts on the server and some moderate usage. Generally its working fine, but I have some problem related to I/O usage.
Normally, I have to backup my websites, and I do it weekly. When the server is doing backup, system services stop working and later when I check sar, I see high CPU usage. I also receive notifications about services failure and recovery.
I understand that cPanel default backup eats my ressources, but its consuming all of it, as it is configured to run over night, when there is very low traffic.
So, tomorrow when I ssh to server and start coping all those backups to my backup data space, there is high CPU usage again. Websites are limited, emails are slow, everythings working bad.
So, I guess that my server is too slow for doing backups and even copying backups to another server or directory on the same server.
But I need those backups! Its too risky for me to disable backups.