To answer your question:

http://thedata.org/

Many of the problems associated with digital (electronically mediated) data storage also apply to analog storage. A terrorist could equally likely target a physical library or a software library, and the former scenario would have even-larger capacity to erase information.

The problems pertaining to energy requirements, degrading or obsolete formats, and the dependence on read/write devices are easily circumvented with enough planning. For example, there's a perilously large, imminent data loss owing to the degradation of celluloid films.

Any problem with a particular electronic medium can be circumvented by transferring to another medium. So if we want our archives to be robust to, say, an EMF pulse, we can archive onto optical media. If we don't like digital optical media we can use analog optical media. Nobody backs up their hard drive onto microfilm but it's conceivable.

The new problems associated with digital storage are mostly related to the politics of intellectual property and not the media itself. I like to pose the rhetorical, "what if the pen and paper were patented and under strict licensing; how would civilization have progressed?" I mostly get blank stares.

If some third party gets the 'rights' to centralize the control of large swathes of our (civilization's) data, and these 'rights' limit others' access to the data, then a large data loss seems imminent. Analog or digital, data should be spread as evenly and redundantly as possible.

"what if the pen and paper were patented and under strict licensing; how would civilization have progressed?"

Wasn't this more or less the situation in medieval Europe where the monasteries controlled the written word?

"Many of the problems associated with digital (electronically mediated) data storage also apply to analog storage. A terrorist could equally likely target a physical library"

I disagree, but don't wish to go into detail in case it gives anyone ideas.

Ironically, Google and a founder of the Internet seems to be more worried about the coming Digital Dark Age than RG members:

'Digital dark age' could leave historians with no records of the 21st century.  

 Google vice president recommends printing out important pictures, so that they can be preserved for history

Andrew Griffin     The Independent Friday 13 February 2015

Technology could mean that our lives are lost to history, according to experts.

As the way that we store information about ourselves develops, memories stored in files that use older technology are becoming harder to access, Dr Vinton "Vint" Cerf, vice president of Google, has warned.

That could mean that historians of the future are unable to learn about our lives, Cerf said. He compared the potential loss to the dark ages — the time after the Romans, about which little is known because there are few written records.

Cerf recommended that users make physical copies of important documents, so that they will last into the future.

"In our zeal to get excited about digitising we digitise photographs thinking it's going to make them last longer, and we might turn out to be wrong," he said. "I would say if there are photos you are really concerned about create a physical instance of them. Print them out."

But even that might not work, since historians often don’t realise what the important documents of a time are until centuries after those that made them have died.

"Some people make the argument that the important stuff will be copied and put into new media and so why should we worry," Cerf said. "But historians will tell you that sometimes documents and transactions images and so on may turn out to have an importance which is not understood for hundreds of years. So failure to preserve them will cause us to lose our perspective."

The author John Harris is also very concerned about "a lack of historical sense, a pervasive contempt for the wisdom of the past". (Guardian Feb 21st 2015, p 33).  The situation with libraries is worse than I had thought.  Manchester has modernised its Central Library, dumping or pulping 240,000 non fiction books that were "duplicates, outdated, or otherwise obsolete".  The Nazis, at least, had more believable reasons for destroying books.   As Harris notes, "precious things are now only a corrupted hard drive or system upgrade away from being lost, for good".  "Is there a cure for all this past-blindness".  His suggestion: reading.  But every few months I find yet another academic library that I used to rely on has "modernised",  old books either dumped or entrusted to that fickle friend, the Internet, to be replaced by a trendy cafe area.

As it so happens, John Harris was on BBC Radio 4 this morning with a short programme on autism, something he has to read a lot about since his son is autistic.  When I realised the large psychiatric library I used was going to self-destruct, I decided to look fairly randomly through the large stock of "obsolete" or "non-relevant" journals and books on the open access shelves for pre-Kannerian cases of autism (i.e. before WWII).   As I had suspected, I was able to find about a dozen cases.  I think some of the more obscure sources I found are lost for ever, or so hard to locate they might just as well be.

 "I think that a challenge is to define / state / decide  what digital data are really  needed to be archived and be usefull after 30 years"

I have absolutely no confidence that this is being done sensibly, or indeed that this is ever possible.  To give one example, one book I rescued from the dump bin was a biography of a Nobel Prize winner.  On opening it up, I saw that it had been loaned to a major US university, indicating that no copy of this book could be found in the US, only in the UK.  Other now-rejected books had been sent over from Germany to rescue them from Nazi bonfires.

Nowadays, we see and judge the past through the prism of the present.  Hindsight and retrospective justice are dominant.   I can quite see some librarian confronted with a stack of irreplaceable old anthropology texts thinking that those containing any indication of imperialism, racism or sexism should be destroyed to protect impressionable modern minds.

I would hope that the span of useful human knowledge is greater than 30y, otherwise why bother with history at all?

No one has bothered to contribute here for the last two years, including NHS employees.  Had they done so, they might have been giving more thought to computer security and hence avoided the recent worldwide ransom-ware attack which has seriously affected NHS computers.  I had not even considered criminal extortionists when I originally put up this question.  I am still not convinced of the long-tern security of digitized academic research, especially that in old journals that are facing extinction.

"However, patient records, which have shifted to being largely electronic, are not available expeditiously in the event of a "system downtime".

Ideally, this should not be that big a problem, and it would not be one if everyone makes an effort to remember their own basic medical information, such as medication allergies, chronic illnesses and regular medications. At the end of the day, we are responsible for our own health.

Information technology makes the sharing of complex and voluminous data easy, but every patient should take responsibility and ownership of their basic health information.

Recent events show that systems are not infallible, and provide yet another reminder on the dangers of over-reliance on technology.

Liu Zhenghong (Dr)"    staitstimes.com May 18 2017

"The Internet is said to never forget...I am not so sure...

Many of my compulsive internet searches for articles or documents I am convinced should exist tend to lead up a garden path to what is known as 'link rot' or 'digital decay'.   You will be familiar with the experience.  You click on a link, perhaps from your personal email archive, a news story or the footnote of an academic paper, and the site you arrive at is dead.   In its place is a menacing 404 error message...

Material public records have always been subject to loss, destruction, deletion or amendment.... We used to be aware of these risks and thus saw value in archiving and duplicating records independently.   If we place too much faith in the eternal memory of the internet we could, in the worst-case scenario, be heading towards a new type of dark age: one where public records simple cannot be relied upon."

Izabella Kaminska  Financial Times Aug 16 2017 p 11

Agreed with @Anthoony G Gordon.

There was an interview recently on BBC World Service Stumps with a county cricket scorer.    Whilst she did see advantages in digital scorecards, she was very wary about going fully digital as she was concerned that such data would eventually get lost in cyberspace or irretrievable.