I'm not familiar with it personally, but it seems perfectly nice to me. I'm really not sure why, but I find either Sohana or Suhana to have more of an South Asian feel to them -- Sahana seems like it could be from any number of different origins. I also find the former two totally intuitive to pronounce, whereas I second-guess myself a little with Sahana (maybe because it's fairly close visually to Savannah?).
In any case, I think people will almost never assume the name is made up if your last name is identifiably non-Western, or if at least one parent has South Asian heritage. If you are a 100% Anglo family, though, then a lot of people may figure you fabricated it.
It looks like a mesh between Susannah and Hannah to me I did not make the Sahara connection. I would definitely think it was from another culture. The sounds mixed together in that particular way sound a little awkward to my ears, sounds really broken up and doesn't have a fluid flow to me.
It's an Indian name, very popular there. It's pronounced something like Suh-huh-nah (kinda hard to explain). It's of Sanskrit origin, means 'tolerance'.
I went to college with a Suhana, so I'm more familiar with this spelling. She used the occasional nickname of Susie, and I fell in love with it. Plus, Suhana is very similar to Sue Hannah, which should be easy for most Westerns.
With Sahana, I fear most Westerns will see Sahara when written, and hear Savannah when spoken -- at least initally. But, it is very straightforward and pretty, that it could be workable.
Sohana is nice and easy too. All in all, it's a very beautiful name in all forms. I think it might mean, "melody" or something like that.
I don't think it seems made up; it seems Indian/Middle Eastern. It's only okay if you're from the background the name is. Otherwise, it's tacky.
I think it's cute and interesting. I would think an African/Native American/Russian/Eastern European background. Which is of course the most reasonable combination, but I could see it in all of them.
Definitely the Sahana spelling. Suhana sounds tacky (Sue-Hannah?), Sohana sounds odd.
I think it's really cool.