There are number of problems with this, the big one being the difficulty of reading and writing DNA. In addition, while storage may be very dense, it is somewha

There are number of problems with this, the big one being the difficulty of reading and writing DNA. In addition, while storage may be very dense, it is somewhat environmentally sensitive. IE a single cosmic ray can cause DNA breaks. This principle has been proposed to make a dark matter detector using sheets of synthetic DNA on gold[0]. It's also been determined that DNA has a half life of about 521 years[1]. Of course DNA's overlap does help with this in addition to the fact we can massively replicate DNA. Being able to massively replicate DNA can let us copy the same data an inconceivably huge amount of times so that we have a huge amount of redundancy. In addition, this ability has let us sequence DNA from neanderthal bones from ~50,000 years ago. But we might be able to do better using more stable molecules than DNA. Peptide nucleic acid or PNA is an interesting option for this. It binds together stronger than DNA while maintaining a lot of the benefits of DNA. Now if we're willing to throw away complementarity we could potentially store information with peptide sequences(proteins). We have recovered peptide sequences, albeit short fragments that were repeated numerous times, from dinosaur bones[3](although there are some worries with contamination here). Peptide sequences might get tangled up and will almost certainly be more difficult to read. We could potentially use a similar chemistry to that used in plastics for even more stability, although synthesis of large amounts of long sequences will be extremely difficult. [0]https://www.technologyreview.com/s/428391/revolutionary-dna-tracking-chamber-could-detect-dark-matter/ https://www.technologyreview.com/s/428391/revolutionary-dna-... [1]http://www.nature.com/news/dna-has-a-521-year-half-life-1.11555 http://www.nature.com/news/dna-has-a-521-year-half-life-1.11... [2]http://www.nature.com/nature/journal/v505/n7481/full/nature12886.html http://www.nature.com/nature/journal/v505/n7481/full/nature1... [3]https://en.wikipedia.org/wiki/Peptide_nucleic_acid https://en.wikipedia.org/wiki/Peptide_nucleic_acid [4]http://www.nature.com/news/2007/070409/full/news070409-11.html http://www.nature.com/news/2007/070409/full/news070409-11.ht...