We have hard drives, we have silicon memory, but if you really want to do some serious data storage you will have to look at DNA strings. That is exactly what researchers from Microsoft and the University of Washington did by creating a DNA drive.
It is all very different from what we know. The ‘drive’ looks more like a collection of bottles from the local chemist and easily fill up a desk. Just a single write and read cycle of 5 bytes took almost 21 hours!
But, the promise is there, DNA storage density is many, many times higher than todays technologies and where we need a complete warehouse with servers now, in the distant future it can all be in one single ‘bottle’ - indeed, a message in a bottle.
Nature Scientific Reports published a report describing how DNA can be used for data storage, it is very detailed, but you have the whole weekend to give it a good read. You can find it here https://www.nature.com/articles/s41598-019-41228-8