If I did get one, I wouldn't get one that tended to silently fail, since that would pretty well defeat the purpose of thinking my disks were redundant, wouldn't it?
If you were talking about anything else, like a normal hard-drive, fine, of course it can fail silently. But the whole thing that a RAID drive is, is another layer on top of hard-drives, to make them redundant and chirp loudly when one dies or starts having wrong data and has to be removed, so that you can replace it and rebuild the RAID.
I mean, all the RAID controller does is write data that is always redundant (even when it thinks all drives are working fine). How is it not possible for it to check for this consistency as well? Especially in Raid-6 etc configurations, which are even more consistent?
Of course, on a probabilistic level random bit rot means "nothing is certain", but on a practical level, how can you not expect a raid controller not to fail silently, when all it does is corral redundant data around, create checksums, verify what's written, etc. It's the whole reason it exists.
To me this is like saying that a checksumming algorithm should be expected to sometimes fail and just return a checksum chosen randomly from the space of all possible checksums, instead of the checksum actually produced by the algorithm for that data.
That's ridiculous. I shouldn't have to even think about putting another layer on top of the checksum, so that I can checksum it. The very idea of having to do that means you don't have a checksumming algorithm.
This thing should be right up there with bitrot causing bash to execute an rm -rf whenever you drop down to root. Sure that's possible, but that's not even in the scope of anything you have to think about.
To me, a RAID is a layer on top of hard-drives that makes them redundant. Any controller that has a realistic chance of failing silently simply does not fit that definition.
Please note that I have not said "it is likely to fail" or "you should expect that it will probably fail." I agree that it shouldn't be something that keeps a person up at night. But the simple fact is that, when data is important, you should prepare for that possibility (and others) by backing up. RAID does not solve all problems, and it is not guaranteed, as unlikely as failure might be.
Moreover - in saying that it simply isn't RAID if it ever fails silently, you're attempting to define away a nonsemantic problem. The point of a starter motor on a car is to start the engine. If the starter motor fails to start the engine, I guess I could make an Aristotelian argument that it has ceased to be a starter motor, or even perhaps that it was never a starter motor in the first place. But what practical good does that do anybody?
All hardware has the potential to fail. Yes, people should buy hardware that is less likely to fail. I'm pretty sure they already do that, though.
