Actually, there are alerts/system events about the disk usage.
There are two entries in \Vontu\Protect\config\IncidentPersister.properties:
# archive.severe_disk_usage.percent is how full the disk where the Message Archives are stored can be before generate a SEVERE system event
persister.archive.severe_disk_usage.percent=90
# archive.warning_disk_usage.percent is how full the disk where the Message Archives are stored can be before generate a WARNING system event
persister.archive.warning_disk_usage.percent=80
On the other hand, there are no such entries about the processor usage.