I have 2 ISPConfig server named server1.test.com and mirror.test.com (which mirrors ISPConfig config from server1).
On the server1, I only backup these directories plus all databases dump:
File = "/etc"
File = "/root"
File = "/usr/local/ispconfig"
File = "/usr/share/phpmyadmin"
File = "/var/www"
File = "/var/log"
File = "/var/named"
I tried to exclude the /usr because it take so much space.
The ISPConfig on server1 can be successfully restored with the backup set I used.
After restored, server1 and mirror still replicates.
Can you check if we can safely exclude the /usr and some other directories from your backup script?