I think this thread seems to concentrate all to much on hardware failure (specially regarding SD/writing to disc). And maybe this is correct. What worries me is, this is a rather general matter on all platforms and all kinds of storage systems. And there is really only one solution - Backup.
You can not have a 100% fail-save system, and specially not a system like OpenHab running on an Rpi from a SD card. So while it might be a good idea to use an external HD for your system, you still need to backup the system.
Now.. I doubt many disagree with that. Well, what really makes me wonder - Where is the backup option in OpenHab? Heck, we´re building automating systems here, and yet, for backup, there doesn´t seem to be any good and easy automatic solution..(easy - It has to be easy for people to use it).
Why ??
I have notices in openhabian-config there is something called Amanda backup. To be honest. If thats what it takes to do a backup. I´ll rather take the chances, make some manual copying from a SSH client once in a while, or otherweise start all over.. This is NOT a motivating backup solution for anyone else, than people who already knows everything about liunx. I´m not one of those! Untill I started of with Openhab several months ago, I knew nothing about Linux. Today i know some, but thinking about it. First thing to know should have been a easy backup solution for “dummies” likes me!
I wonder why there isnt an option inside PaperUi to configure and run somekind of backup system. A simple scipt which add all important files into a zip file to download. Maybe even an advance option to do it automaticly and save to a network share path, cloud, whatever. And a super advance option, running in a crone job.
My bet is, this would motivate users to do more backups.
But backing up Openhab may only be half the need thing to do. Reading about the Amanda backup it also mentioned someting like z-wave networking. I admit, I never thought about this untill I read it. But one actually have to make a backup of the z-wave network as well in case the controller fails. Well, now things gets a bit complicated. And then I wonder again - I have the z-wave binding installed. Why isn´t there an option to backup the z-wave network from the binding as well? This leave me to search and install some 3.part utility to do this backup.. But why? Is it a limit in the Rpi where my z-wave controller is connected to? I doubt that, to be honest. My windows PC can do it. But my controller is connected to my Rpi. So it makes not sense to remove the controller from the Rpi, place it in my PC to do backup, and then put it back to my Rpi. It does not make the over-all backup procedure an easy to remember thing. And it most probably ends up with not beeing done.
My guess is, if developers of systems (software in general) first thoughts was, “What to do when things goes wrong” (again note, it´s not an “if” question). Things like bad SD cards, hardware failures etc would be short term discussions in general. (And I would have saved myself lots of time writing this 
)
Well just some thoughts I have been doing lately.