"Also as all this data is stored magnetically- I can imagine that at some future date when historians are researching the 21st century- there will be a big hole in the data due to Solar activity or EMP that wiped everything."
That's the doubt that lurks in the back of everyone who deals with data storage. There's no answer to it, because of course our current methods of data storage are vulnerable in several ways. We make constant server backups to protect against hardware failures, and we protect our secure data storage facilities against all kinds of threats, but that's not the full story.
The real worry is that the data will degrade over time, and unless we repeatedly copy to new media we will, in the end, lose the data. We are therefore locked into the repeat copy cycle - important data will have to be rewritten at intervals if they are to survive beyond the life of the media on which they reside. As things stand, tests on CDs and DVDs give life expectancies for recorded data of between 50 and 100 years, but nobody really knows for sure, and storage conditions (humidity and temperature) play a large part in the process.
Nobody knows about solid-state storage devices, or whether the life of the device is the same for the data stored on it.
What we do know is that it's possible to store data in other ways for very long periods. Clay tablets with cuneiform writing that were made approximately 3000 years BC in what is now Iraq are currently being decoded.
Perhaps in some areas we haven't come as far as we think we have.