Wow Edwin, there's just nothing worse, is there? This is about as bad as finding out a hard drive has failed the very moment you have an incident you need to retrieve.
While I'm the first to say that ftp and/or cloud recording is by far the best option, sometimes the bandwidth isn't available from your local internet service providers such that these solutions become feasible. However, plenty of NVRs these days have the ability to record channels of video from like branded DVRs, in other words, if you have a Brand X DVR, you can often purchase a Brand X NVR, hide it, and record channels redundantly across a small parallel LAN or even a crossover cable. This solution will be the most stable, and although has some greater upfront cost, has no recurring cost like other subscription-based cloud services. So too, you could rely upon a remote DAS device, but the question becomes whether or not the DVR/NVR you're using is storing recorded video immediately to that storage device, or on a scheduled basis. Same issue with cloud storage-- is the video being written realtime or scheduled, and if so, what about buffering, etc? There is also the concern with a traditional NAS or DAS as to what happens when video (data) is in the middle of being written and a network connection drops-- is the video (data) corrupt and unusable? This is why I like using two like-branded devices, a DVR & NVR directly connected, or an NVR and NVR directly connected; put one device on a rack or shelf where it would normally be placed, then hide the other device somewhere else-- the devices will archive in realtime, and you're less likely to miss something in the event one machine is damaged or stolen.
There's always lock and key solutions, too. I have a handful of ventilated Middle Atlantic lock boxes I've used or recommended in the past which both protect the recorder from the elements and theft/damage, and while they CAN be costly, they generally get the job done. Another option... I have an integrator now who will open every DVR/NVR he installs, drills around four holes in the bottom of the chassis if it isn't being rack-mounted, and uses lag bolts to attach the DVR/NVR to its intended installation surface, whether that be a wall, countertop, or ceiling. He then uses tamper-proof screws to close the DVR/NVR chassis up. While this all seems rather crude, it makes theft a lot more involved, and as history has shown, thieves have been known to either give up on trying to take a recorder, or beat and smash the hell out of the recorder because they can't remove it. In that case, the hope is that the hard drive hasn't failed in the process, which so far has not happened, though that should never be discounted as a potential hazard of this type of installation.
You COULD opt for the best of both worlds... Install a DVR/NVR with an NVR on a small local LAN as backup, then bolt them each down or stick them in lock boxes.
That's what I suggest. If you need help identifying a brand that will do realtime parallel backups, feel free to ask.