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