Identity and data are kinda tied together.
They aren’t stored togethet by default, but you’re free to do so.
It’s useless without its data (unless it’s brand new).
However, if your disk storing data starts having bad sectors, losing a few Storj fragments isn’t a big deal if you notice the issue soon enough and switch to a new disk: your audit score may drop a little but your node should be alright, and the Tardigrade network will rebuild lost pieces eventually.
However if the identity got corrupted, and if you have no backup of it, that’s the end for your node and all of its reputation/data/held amount will be lost for good.
So wherever you put your identity, it still feels to me like it’s worth backing it up somewhere safe. Just in case.