You are taking a calculated risk and your risk is the inconvenience of feeding DVD’s back into your machine for a week (or two or three).
You are arguing that since the probability of total (or significant) data loss cannot hit zero then it is pointless to go any further? I don’t agree with that.
I agree that possibly even the majority of Drobo owners rely on that one copy of their data, but that does not make it a good decision. Some are sucked in by the marketing hype. DRI includes this “quote” on their “Customer Success Stories Link”:
“Simply knowing we can’t lose data and that there is always redundant backup on the fly, has given us a great sense of security.”
Personally I think that is an egregious lie, and I’m backed up by the “Best Practices” FAQ put on the site by the engineering side. Obviously marketing and engineering are at odds on this issue and obviously engineering has history on their side.
Some refuse to back up their Drobos because “I spent all that money to guarantee my data was safe” or some such thing (it’s all in the forum archives). They are deluding themselves and refuse to admit it even when confronted by the facts.
Some come here on their hands and knees BEGGING and pleading for someone to resurrect their failed Drobo array. They apparently have more than DVD rips on the Drobo :-(.
The classic case was a guy that loaded a pile of drives into his Drobo, feeding the original disks into the Drobo as he went along. He even added a 3rd or 4th disk to the Drobo unnecessarily and, of course, he lost the array before he was even finished. He was one of the beggers and pleaders and that was sheer stupidity (or blind faith in DRI marketing, depending on your point of view).
I suspect that the probability of losing data over a 10 year period approaches 100% with no backup or redundancy. I suspect the probability of losing a Drobo array over that period is about 10% (for any and all reasons, some beyond the control of the Drobo).
I suspect a second copy takes that down to the 2-4% area, depending on how it’s managed, and each successive copy cuts the probability in half, more or less.
It only costs about $330, max, to make a copy of a Drobo array in a Win or Mac readable format, not a thousand. So it all comes down to what your data is worth. My data is mostly images that are irreplaceable. The most replaceable part is my 600 or so music CD’s ripped into iTunes but even there I don’t ever want to have to do that job again.
I keep 3 additional copies of my Drobo data. all in native OS readable form (NTFS). I know I can read them because I do binary DIFs from time time to time. As disk gets cheaper I make more copies :-). I have a 4th copy of my images - straight out of camera - set aside specifically over concerns about corruption. Yea, I’m anal but I’ve run my probability down to near zero for very reasonable money (relative to the value of the images and what it cost me to acquire them).