No idea what the omv job does, but having 15 min jobs is not unusual. Nextcloud and ownCloud also recommend their cron.php run every 15 minutes e.g.
Great that it worked
@Rock64 oh whoops, too fast assumption. We do not actively add this cron job as far as I can see within code. But okay it seems to be part of other device images as well. Hmm maybe we should check/ask for reason for this job every minute and see if this really makes sense if file servers are in use, perhaps adding it to our samba etc install script, but remove it as default from our images.
Quick web search shows this in combination with Rock64, Pine64 and NanoPi indeed ad well, often in combination with openmediavault. Hmm ugly thing for me...