I don't have too many HDDs but they are big.
I'm unifying my data by hand right now because I don't have a permanent dedicated machine and I am too lazy to automate it.
Besides I move certain pieces of data with me regularly physically, and I am not sure how I want to manage it too.

I got more big drives and I am moving stuff from a 16 tb drive to an 8 tb one currently because I overestimated the size that I would need so that I can add the 16 tb to my torrent server.
And I will have to put stuff from the 16 tb to the 8 tb so that they swap places too.

It will take 11 more hours.
And it will take another 11 hours to go the other way.
And I will have to encrypt the 8 tb beforehand.
I am demotivated.

I wish I could afford a tape reader and move to tapes already.