@jamesoff @rhoot @stefano When I managed such things in the past, I had the backup script use zabbix_sender to send a value to Zabbix and then alert if that is missing, like you just said.
But after one incident I also added monitoring of backup size and alerting if it changes by > 10% from the previous.
If backup starts getting failed DB dumps, it's good to know early that "hey, backups just dropped in size by 90%" 
Also, if a backup suddenly grows a lot, something's weird.