Systemd Service/Timer -- Oneshot service w/ timer executes multiple times and failed w/ 'start-limit-hit'

Question

I want to start a command (unison) every 5 min as a systemd.service via a systemd.timer unit. The '.service' file alone runs fine. However when it's started by the timer unit, it runs multiple times and stops with these errors: Start request repeated too quickly. and Failed with result 'start-limit-hit'. But why?

I start the timer service like this: systemctl --user start service.timer.

The files are located in: $HOME/.config/systemd/user/.

sync.service

[Unit]
Description=Sync Service

[Service]
Type=oneshot
ExecStart=/bin/zsh -l -c "unison -batch %u"
ExecStartPost=/bin/zsh -l -c 'dunstify "sync ~"'

[Install]
WantedBy=graphical.target

sync.timer

[Unit]
Description=Timer for Sync Service

[Timer]
OnCalendar=*-*-* *:0/5:*
AccuracySec=5s

[Install]
WantedBy=timers.target

The unison command syncs over the network into a server via ssh with a password proteceted keyfile. A ssh-agent instance is running by the user. That's why i have to use a login shell: zsh -l -c "...".

Answer 1

For the record: OnCalendar=*-*-* *:0/5:* is simply wrong. OnCalendar=*-*-* *:0/5:00 does stoping the multiple execution.