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Which format has the longest shelf life?


chauncey alan

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Film stored as b&w separations in a climate-controlled vault should last 500 years... of course, I'm talking about processed film, not unexposed stock.

There is a proposed long-term storage format called DOTS:

http://www.group47.com/Group_47-DOTS_Technology_Overview-WEBSITE.pdf

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For the everyday Jane or Joe, 'M' disc is rated at 1000 years.

I have optical media archival tests underway now to be completed next spring. So far M disk has far outlasted regular DVD in sun exposure. Silver DVDs die in 3.5 weeks. Gold DVD lasts about 4.5 weeks. The old Kodak gold DVD lasted about 5 - 6 weeks. M disc has been in the sun for 6.5 months and no issues at all. 

https://en.wikipedia.org/wiki/M-DISC

M Disc can go up to 100gb, but is a variant of Blu-ray. So far M Disc Blu-ray have held up, but will not know until tests are complete if M-Disc Blu-ray are as good as original M Disc DVD.

It is good to have your material archived on as many things as possible. But flash drives are said to lose data after 10 years if not accessed. I've tested flash drives after 5 years with no access and they worked fine. 10 year tests are forthcoming.

Silver CD-R's have a longer life than silver or gold DVD-R's. Silver CD-R's lasted almost 3 months in the sun. But not much you can use CD's for nowadays due to low storage ability.

Here is a test on a 15 yo CD . This is from a CD video recorder.

https://danieldteolijrarchivalcollection.wordpress.com/2019/01/14/15-year-cd-r-archival-burn-test/

Blue, dye based CD's are terrible and die after a couple weeks in the sun.

Some critics poop on optical media for archival work. They like tape. I have CD's going back to 1983. They are still readable with no end in sight for access ability. Tape going back to the early days is very hard to access do to the lack of hardware. Don't discount optical media for archival work. Only shortcoming with optical is low ability to store mass amounts of info.

Too bad they didn't do some archival tests on all the faded red film we have now. Maybe they could have developed something better.

Archival testing is of the utmost importance for preserving history. 

https://danieldteolijrarchivalcollection.wordpress.com/2017/08/19/just-because-it-is-marked-archival-it-does-not-mean-it-is-archival-2/

Edited by Daniel D. Teoli Jr.
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17 hours ago, David Mullen ASC said:

Film stored as b&w separations in a climate-controlled vault should last 500 years... of course, I'm talking about processed film, not unexposed stock.

There is a proposed long-term storage format called DOTS:

http://www.group47.com/Group_47-DOTS_Technology_Overview-WEBSITE.pdf

How much does DOTS cost?

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DOTS doesn't really exist yet. it's in development.

I think the OP is looking at the problem the wrong way. We are reliant upon commercial tech companies to provide us with the formats to make and store images. There's no getting around that, and film was no different. These companies are going to change things constantly, and they're going to try to outdo each other with newer and better formats. Film definitely has long term advantages, and as David Mullen suggests - B/W separations are the current best format for long term storage (but this is wildly expensive both to make and to store and maintain - you can't just stick it on a shelf in a basement, you need climate-controlled storage and the ongoing costs - facilities, electrical, maintenance, labor - are enormous). 

With digital media, the only sane solution right now is to migrate, migrate, migrate, and build lots of redundancy into whatever strategy you use for storage. If you're looking to store a film, I would start with hard drives, which give you quick and easy access in the near-term, but will fail eventually. Multiple copies, in multiple locations, helps with this problem. But don't expect these drives to be good for more than 5 years, to be safe. They probably will, but don't count on it. Migrate the files every few years to new drives.

As a more long term backup - maybe 8-10 years - the current best format is LTO. It's robust, it's ubiquitous and the development of it is an open book, with a well defined roadmap going out many years. It's designed by a consortium of companies, so it's not subject to the whims of one manufacturer. Major enterprise-level backup systems (banks, medical, government, defense, etc) rely on LTO, so it's not going anywhere any time soon. Amazon Glacier is LTO.  Stay a generation behind what's current, and it's reasonably priced.

Aside from the immediate problems of specific media (a given hard drive or LTO tape) failing, you have the larger issue of changes in the underlying technology that's used to power those devices. For example - SCSI was the only way to connect drives, printers and other peripherals for decades. Now it's all but dead as an interface to computers (the protocols live on in iSCSI and SAS, but that's software, basically). If you put stuff on a SCSI drive 20 years ago, it's going to be very hard to get the files off of that drive now (if the drive still spins up), and much harder 5 years from now. The same will happen with SATA, and USB, and all other interconnect formats. It's in the interest of the tech companies developing these formats to constantly move you to something new, to sell more product. 

So the best way to look at digital archiving is to see it as a constantly evolving process, and just roll with it - move your data to new formats. Keep checksums to ensure there's no corruption. Keep multiple copies in different locations on different formats, so if one goes bad you have a viable replacement.  

Trying to find a digital equivalent to film, where you can stick it on a shelf and more or less forget about it for a few decades, will lead to disaster and disappointment in the future.

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