After trying backup server to server (this tutorial):
https://manual.seafile.com/deploy_pro/real_time_backup.html
I have run in to this issue:
[root@9xi8 seafile-server-6.3.4]# sudo ./seafile.sh start
[06/10/19 11:02:34] …/common/session.c(132): using config file /var/www/html/conf/ccnet.conf
Starting seafile server, please wait …
Failed to start seafile server