I recently backup and restored an ISPConfig 3 server
root@za-02-802:#mkdir -p /backups/os/ispconfigbkup
root@za-02-802:#cd /backups/os/ispconfigbkup
Back up all of the databases on a server:
root@za-02-802:/backups/os/ispconfigbkup# mysqldump -u root -p –all-databases > all-database.sql
root@za-02-802:/backups/os/ispconfigbkup# tar -pczf completeserverbackup.tar.gz /backups/os/all-database.sql /home /var/vmail /var/log /var/www /var/lib /etc /opt/letsencrypt /usr/local/ispconfig
Restore to a New Server or Reinstallation
root@za-02-802:#mkdir -p /backups/os/ispconfigbkup
root@za-02-802:~# cd /backups/os/ispconfigbkup
root@za-02-802:/backups/os/ispconfigbkup# tar xvfz completeserverbackup.tar.gz
root@za-02-802:/backups/os/ispconfigbkup# mysql -u root -p < all-database.sql