It's easy to be negative with these things, from my experience 'a' secure back up is away from original files, by example if your house burns down then all HDD are lost in the fire so you could have a few back up methods such a NAS of external HDDs' but they would be gone in a fire, flood etc.

So I looked at a cloud solution (justcloud) seemed good until I realised that to move my archive of RAW images to the cloud would take 7.5 days at 8Gb/24 hrs speed, that's JustClouds best optimisation.

Then you consider downloading 30Mb for a single file it gets time and money consuming.

So in the end I sprang for a 4Tb NAS Raid 1, high initial cost but in the end will reach break even, all I have to remember now is to grab it when the fire starts

David