Thanks, now I see what you are getting at. I could see an option where the program could try and access the file and read any fault codes back and then send a reboot command if the file cannot be accessed. Something tells me this is probably a bad idea. Probably get caught in some endless loop.
Of course the entire file could end up corrupt and all the data would be lost without doing what you said and create daily files or hourly (whatever time span a person could live with or without).
Other option is to improve the wireless link and make it more reliable and just have the Yun push the data up to another server that's at the house.