Just thinking out loud, as I have an open slot in my drobo, and a 400GB PATA drive laying around that I am not using.
Has anyone tried this?
It looks kinda tight in there, but if you don’t push the drive all the way in so the clip snaps, you might be able to fit sata -> pata adapter in there.
If it does fit, would the drobo be able to use it, get confused or (even worse) be harmed?
most of the ones i have seen require separate power (they only process the data signal - the assume the drive has a 4 pin molex connected to it separately and then they need a floppy type power supply plugging into them convertor to make it work
in theory it would work, but considering how ridiculous cheaper drives are, i woudlnt chance it
Good point. I’d probably spend almost as much on converters and wires as it would cost me to buy another 400Gb drive. Storage really has become ridiculously cheap in the last 5 - 6 years…
It just feels so wasteful to have the drive laying there not doing anything and an empty slot in the drobo 
well… ebay the drive, im sure someone will find it useful, and you can put those funds towards a 1tb ($60) sata drive 