"Stop asking about media longevity and ask about file longevity."
"don't think anymore in terms of reading from media, you think it terms of sending an NFS (or HTTP or whatever) request."

EXACTLY!

Now, where can I buy a system to do this that isn't wrapped up in some proprietary software mechanism?
The only large-scale archival systems you can get today are sold by the likes of EMC for Sarbanes–Oxley compliance.

"how to preserve digital data for long periods of time."

The one advantage of digital data is that is is easy to make idential copies.

Make lots of copies, with redundant encoding and error checking
Spread the copies in different physical locations.
Migrate it to a new medium as necessary (bit density increases over time)

Depending on ANY single copy surviving and being able to be read at some point
in the future makes no sense.

If you REALLY care about the data, you will spend the time to migrate it
to newer media.

"User 460244 is talking gibberish and does not understand the problem"
"The magnetization areas in floppies are way above the flux areal size limits."
"You just read the analog signal from the heads"

Inductive heads only detect flux transitions. Are you proposing the use of a MR transducer, which can directly measure flux?

"You could just use a block compression algorithm."

Tell that to the people writing compression programs.
As was mentioned further down in the replies, there doesn't seem to be any freely available software
for creating distributed archives with redundancy and error correction. With the amount of data needing
to be archived, and the lack of reliable storage media, I don't get this at all.

This is a totally non-obvious trick that I came across this past year for mitigating binder failure
on floppies. Spray the surface with white board cleaner before you try to read them.

This should only be used as a last resort if you know that disks of a similar age and condition
shed rapidly, and obviously clean the heads before and after you try this.

"Magnetic media like tapes and floppies use a binder (glue) that becomes corrupted with moisture over time, allowing the metal-oxide particles to flake off."

This isn't actually the hydroscopic failure mode of 1/2" computer tapes. The tape becomes sticky and will glue itself to the head if the tape ever stops moving,
for example if the transport attempts to do a reread.

You need to bake computer tapes with a lot of airflow for the process to be effective. I have recovered thousands of tapes sucessfully this way.

This is a COMPLETELY different problem. There was no basic difficulty in recovering the flux transistions on the Cray disk pack,
which is the problem that this guy has.
If you can't get good sector data, you have no hope of recovering something that has been compressed without
error correction built in.
I'd be happy to hear about an error recovery process for corrupted ZIP archives.

don't

Legacy systems have 60Hz real-time clock interrupts derived from line voltage.
These sorts of systems are STILL IN USE.

As well as any AC powered LED clock module from the 70's.

History is written by the victors

Given that attitude, no software would survive from companies that have gone out of business, since there is nothing of commercial
value there.

The short answer is "NO"
It is much more efficient for a researcher to search OCRed indexed content.
You can literally save years of time researching a topic if documentation and artifacts are available somewhere on-line.
It also helps with peer review. You can now reference hundreds of documents that reviewers may not have physical
access to.

As the software curator at the Computer History Museum, the compromise that works most often is releasing
code for non-commercial use. From a software preservation standpoint, it does put it in an institutional
environment where the code can be saved and studied in the future. The most recent agreement is with PARC
releasing the code for the Xerox Alto.

Consider donating it to the Computer History Museum

http://americanlibrariesmagazine.org/news/07142010/california-groups-oppose-library-privatization-talks

"Several nonprofits in San Joaquin County, California, are sounding the alarm as the county board of supervisors considers the privatization of the management of Stockton–San Joaquin County Public Library"

and

"Public libraries in Camarillo, Santa Clarita and Ventura have all been targeted for a takeover by Library Systems and Services (LSSI), a private company headquartered in Maryland and majority-owned by the private equity firm Islington Capital Partners."

It did survive. NCD, Tektronix, and others sold graphics terminals which supported X
It was reinvented in the Windows world as thin clients.
We didn't LOSE anything, the market decided the difference in price between a PC and an X terminal wasn't worth the bother.

The guy that posted Bill English's Alto video is on crack if he thinks this is from 1974. The mouse is a Hawley "Mouse House" mouse from the 80's.
Real Alto mice are more rounded and don't have rectangular buttons. Bill also looks about 20 years older than he should if this were from 1974.