"Failover" location

I have a Mac Mini setup as my Channels DVR server, and have it set to use a folder on an external USB HDD for the recordings.

Unfortunately, at some point today something happened to my external HDD and it became unmounted from the Mini (maybe the drive it beginning to fail?). I discovered the problem, but only after the DVR missed several recordings. Simply rebooting restored everything to working order. But, of course, there's nothing I can do to get back the non-recordings.

I'm thinking that it would have been great if the DVR let me specify a "failover" location that it would use in case the primary location is inaccessible for some reason when a timer kicks in to start a recording.

Alternatively, maybe I should look into setting up a pair of external drives as a mirrored RAID?