I’m not sure what the chances actually are, but that much rewriting and shuffling data, if it doesn’t immediately result in data loss it is going to put a lot of wear on your drives. If your largest drive is 8 TB, I’d look for another 8+ TB drive so that you can copy the data and then reformat. Even a slow external drive is likely to be faster than what you’re doing.
I’m not sure what the chances actually are, but that much rewriting and shuffling data, if it doesn’t immediately result in data loss it is going to put a lot of wear on your drives. If your largest drive is 8 TB, I’d look for another 8+ TB drive so that you can copy the data and then reformat. Even a slow external drive is likely to be faster than what you’re doing.