How to receive RAID failure notifications from a Mac mini being used as a RAID device

I recently bought a Mac mini to use as a NAS, among other things. I'm thinking about setting up a couple external drives as a RAID 1 (mirrored) set to help safeguard my data in case one of them goes bad. I doubt I will be using a monitor with the computer very often and I'm afraid that a dialog box or notification will sit there for months, unnoticed, while I continue to use the drive over the network. I would prefer to be emailed or notified on my iPhone. When a disk goes bad, how does the system notify you?