I am doing a full backup of everything to the owner's home currently. I am fortunate in that there is a wireless link to the owner's house and we see 20+ mbps between the studio and his home. With that said, here is what we are doing:
We are using controlready for automation which has facilities for running multiple automation decks per machine, including file sync operations and just about anything else you can think of.
I have tasks running that sync changes between both air machines every 5 mins. I have other tasks that send any changes in audio folders to the owner's house every 10 mins.
I have a nightly backup script that dumps the naturallog database to one of the air machines nightly, this then goes over to the other air machine and owner's home machine within minutes.
we have a 950mhz stl and t1 circuit to one transmitter site with automatic switching.
we have a data link on 902mhz to the other tx site which is less than a mile away from the studio. have not built a backup link there yet, only failure has been ice on antennas, was able to go on 161 mhz rpu temporarily to stay on air.
using comrex bric-link over the t1 circuit, barix instreamer/exstreamer over wireless link.
a system that I am implementing before the end of the month is: multiple ip audio encoders and decoders to bring critical feeds over to the owner's house into his console and give him a path back to the studio for both stations. I'm also going to come up with a solution to transport contact closures in both directions to allow the owner to toggle his home studio on air as well as send over a few contact closures for some sports programming so he can run stuff live at home if need be, with a small delay of course.
In the end, we will be able to go on air from multiple locations, up to and including calling the tx site and patching the phone line on air. I also have enough audio i/o and the necessary switching in place to almost immediately press either air machine into service for both stations should one fail, as these are both primarily satellite fed stations, this is fairly important. I even went as far as using ethernet to rs232 adapters on all audio switchers and satellite controllers and using virtual com port drivers on the air machines so I can map the switchers to another machine on the network remotely.
To top it off, both tx sites, studio and owner's home have backup generators.
It works pretty good for a small town locally owned pair of stations, anytime there's bad weather, we're usually the only one in town on the air and getting information out to the public.