

all good. thanks for exchanging our experience :)
kopia wasn’t running durin the week. I didn’t look into the server configuration since it introduces user handling and that seemed to be overkill for the task but running as daemon would lead to a funcitoning system of course.
this is my kopia.service file in case some else finds it and is interested in it
[Unit]
Description=kopia backup
[Service]
User=root ExecStart=$HOME/bin/backup_kopia
[Install]
WantedBy=multi-user.target
where $HOME/bin/backup_kopia contains
#!/bin/bash
/usr/bin/kopia repository connect filesystem --path $KOPIA_REPO --password $KOPIA_PASSWORD
/usr/bin/kopia snapshot create $HOME/folder_to_backup
and my kopia.timer
[Unit]
Description=Run kopia backup
[Timer]
OnCalendar=hourly
Persistent=true
[Install]
WantedBy=timers.target
the backup is working