Super-long-term Retention of small data files

[Ampera]

if you are seriously in need of really long term storage, and you trust your encryption immensely, just make a shit load of different copies in different forms of media.

Magnetic storage like tapes tend to be a good format to use, but they can degrade over time. If you really have some important stuff, get multiple hard copies, and store it in a few bank safe deposit boxes.

Build a few metal boxes and bury it in a field somewhere.

Throw it on every cloud storage solution on the internet.

Just make sure that the files are impossibly well encrypted and that only you can get to them.

[Rerouter]

Unless you know your box is incredibly well sealed and inert i would say do not bury it in a feild, google is full of too many examples of time capsules, even well made ones seeping and turning into corroded mush after even 5 years.

[SeanB]

Print on archival rated acid free paper, using a laser printer. place between 2 more acid free pages, and heat seal into a 1mm thick HDPE pocket, with a sachet of desiccant material in as well. Then place this in a separate laminated aluminised HDPE package for extra moisture resistance, then seal in a laser welded 0.8mm stainless steel box, and enclose that in pitch 50mm thick, and finally surround with 500mm of hydraulic concrete with a 30MPa strength, reinforced with glass fibre and carbon fibre.

Should last a couple of decades under water, or at least till it is subducted and crushed, so store in an old salt mine.

[David Hess]

High density floating gate storage like NAND Flash has a horrible retention time so it would have to be continuously powered to allow scrubbing to take place.  The problem is knowing which products do idle time scrubbing or scrubbing on read; even if they say they do, they might not.

Hard drives are better than NAND Flash but are still poor compared to alternatives unless you have a lot of data.

Low density floating gate storage like older NOR Flash, EPROM, and EEPROM will last 10s of years if not mistreated.  100 years is a real possibility.

Archival optical media can last 100 years and CD and DVD drives are going to be around for a long time.  Store spare drives also.  This is probably the best inexpensive option.  I prefer DVDs because the media layer is protected on both sides.  Store the disks in jewel cases and do not store anything with them which will outgas fumes which could attack polycarbonate.

Magneto optical media should last indefinitely but the availability of magneto optical drives is a problem.

If you have power, an internet connection, and NNTP access, then encrypt and upload to NNTP.  Periodically download, compare, and upload again in a cycle that depends on NNTP retention.  This cycle could be 6 months or more in some cases.  As a bonus, now you and only you can access the data from anywhere in the world at any time.

In all cases use PAR2 files so recovery from small errors is possible.