OK, looks like they are called "Madras onions," "Samb(h)ar onions" or sometimes "shallots," but they are not what most people call shallots--or eschalot in Australia. (the link in #5.)
One source says they are more like shallots in flavor, but others describe them as "sweet." I also found "Like a cross between a shallot and a red bermuda onion."
I'm only finding them as exports from India. And the only info on growing them was from someone who discovered some of his onions sprouting, so he planted them.
I found suggestions for both shallots/eschalots and pearl onions as substitutes.