An Exabyte of data is 10006 bytes of data (EB), or in binary (exbibyte) 10246 kibibytes (KB). Another way of looking at it is 1 EB = 10006bytes = 1018bytes = 1000000000000000000B = 1000 petabytes =1million terabytes = 1billion gigabytes. That’s a good deal of data.
Using the base pairs A-T and G-C as 0s and 1s, one gram of DNA can store approximately 450 Exabyte of data. That would be equal to roughly some billion gigabytes.
Theoretically, in a shielded and sterile environment, the storage of data would pretty much cease to be a major problem for institutions which have vast amounts of data to store. After all, fossil DNA (mammoths and others) has stored data for extremely long periods.
The article I read came up with the figure $1,500 per Exabyte of data. In fact, data was stored on DNA 5.5 Petabytes of it (700 terabytes) back in 2012 at Harvard.
So…using this method, we really could end up with “Mammoth” hard disks.
Sources:
http://hms.harvard.edu/news/writing-book-dna-8-16-12
http://www.extremetech.com/extreme/134672-harvard-cracks-dna-storage-crams-700-terabytes-of-data-into-a-single-gram
https://en.wikipedia.org/wiki/DNA_digital_data_storage