If you're noticing data corruption on only 2TB it's probably not what we normally call bit-rot. A bit that changes state for no apparent reason within a very large set of data can be described as bit-rot, otherwise it's general data corruption which has many causes which all are understood: Poor media, poor transmission of data, overwriting of data etc. Once you've got the system sorted out so you don't get data corruption, start thinking about the nature of your data. How much redundancy is in it? If it's jpegs the almost none, so a single bit error could be serious to a file. If uncompressed TIFFs then there is a lot of data redundancy and the single bit error might only be an error of a single pixel, which you might not even notice.
And finally, don't expect optical media to be safe from errors. Only use it as part of a DR plan.