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Say you had some sensitive information that you didn't want to store on the internet, was incredibly important to you, and you didn't need to access very often either.

Think of a digital picture taken of your grandma days before her death or something... Very important stuff.

So you load the file to a flash drive, put it in a vault, and forget about it.

When should you re-visit the vault to back-up the data to a newer, futuristic flash drive or whatever they are using to store data with in the future.

What are the chances that the data will have dissappeared or the flash drive become unreadable in 5 years? 10 years? 25 years? 100 years?

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  • If you want the data to be readable in 100 years, think carefully about the file-format of the data. JPEG may not still be in use in 100 years - at a minimum you might want to also store the JPEG spec. You might want to store a copy of the image in a simpler well-documented format. I have some old videos encoded in AVI format on Windows 3.1 which can no longer be read as the, then standard, codec is not supported on 32-bit or 64-bit windows. I have Windows 3.1 install media (1.44 MB diskettes) but no hardware that could possibly run them.
    – RedGrittyBrick
    Commented Jun 16, 2011 at 8:54
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    @RedGrittyBlock: Good point, but others have already noticed the same problem and come up with a solution: FITS. Even so, I would worry more about the USB spec than about the JPEG spec. JPEG decoding is just software, and that doesn't tend to disappear.
    – MSalters
    Commented Jun 16, 2011 at 11:00
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    @redGrittybrick: The OSS project DosBox is capable of running windows 3.1 (albeit without networking or printing) A guide to doing this can be found here: vogons.zetafleet.com/viewtopic.php?t=9405. Maybe with this you can convert the avis to a format still supported today.
    – sum1stolemyname
    Commented Jun 16, 2011 at 11:49
  • @sum1stolemyname, you can install dos and win3.1 with networking and printing in a virtual machine such as qemu.
    – psusi
    Commented Jun 11, 2015 at 22:29

7 Answers 7

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I think that with the current technologies the limiting factor will not be the amount of time the data will be able to be stored on the media without decaying, but the availability of readers. It is hard nowadays to read a 5 inch floppy disk, and almost impossible to read the stack of 50+ years old perfectly preserved punch cards left from my grandmothers education in the university.

So I think you should change the device with more modern every 10 years or so just to be sure.

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  • Good points. Upvote given. Obviously I would be re-visiting the vault every year or two just to take a look at her so to speak. I guess bringing a computer with me and upgrading to the latest possible storage hardware at the time wouldn't be too bad of an idea. So what you are saying is that the information will last forever theoretically?
    – darkAsPitch
    Commented Jun 16, 2011 at 5:33
  • In theory yes, but you could find yourself accessing it for the first time in 100 years, only to have it die on you.
    – KCotreau
    Commented Jun 16, 2011 at 5:48
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    Newer technology is harder than older technology. Those 50+ year-old punched cards probably have the data printed on the front of them. You could read them. Most likely the data is in plain ASCII. Pulling Visicalc data off a MFM hard drive is much much harder.
    – RedGrittyBrick
    Commented Jun 16, 2011 at 8:48
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    Just place a black paper behind the card and scan it into an image... then you can read the image via software.
    – Chris Nava
    Commented Jun 16, 2011 at 17:32
  • Properly standardized software with few pins should be easy to reconstruct, like USB-Serial adapters do.
    – Cees Timmerman
    Commented Dec 6, 2015 at 14:23
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Flash cells are... fairly stable. I'd say in the order of a decade or more. But if you want truly long-life media then you should look to OTP (one-time programmable) media such as PROM or EPROM. Unfortunately I'm not aware of any available in a USB format though, so you would probably have to drop down to using bare chips and a programmer.

And of course, don't forget the 3-copy rule.

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  • I don't like that hesitation, but I do like the word "decade". I have never heard of OTP and will look into that right now. Basically that is what I would be doing with the flash drive however. "Programming" it once and then only ever reading from it for the rest of it's life. And I would only be reading from it a handful of times at that. Shouldn't a flash drive or PROM last about the same amount of time?
    – darkAsPitch
    Commented Jun 16, 2011 at 5:35
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    Flash is meant to be rewritten, so the cells have a little bit of instability built in so that the charge can be force out of the isolated capacitor in order to blank it. PROM is meant to be written to once. Ever. Once the fuse in the cell is blown with a high-enough voltage, nothing will be putting it back together.
    – Ignacio Vazquez-Abrams
    Commented Jun 16, 2011 at 5:38
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    Cell fuses have been known to 'regrow' due to various crystallisation effects and the presence of vapourised fuse material. EPROMs bit storage has a finite life too as you hint due to extremely small amounts of charge leakage. I'd avoid any 'user programmable' technology
    – Linker3000
    Commented Jun 16, 2011 at 8:53
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    Chiseled rock is user programmable and has a proven life time of several millenia ;)
    – MSalters
    Commented Jun 16, 2011 at 11:02
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    @chiseled: The capacity and IO-throughput of a slab of rock is limited, though. That being said, engraving data into rock is the oldest form of data storage i know of which can still be read today - if you know the language and script.
    – sum1stolemyname
    Commented Jun 16, 2011 at 11:55
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All of the prior mentioned are good points, but if I were you, I would not trust only one copy of backup of this sensitive data especially on a flash device. I have had them fail in the past. Storing the data on a small external hard drive actually places the data on the magnetic platter, in this way EVEN if the hard drive fails, you can have experts repair or retrieve the data. Even in this case I would not leave it on the drive untouched for over 10 years, as hard drives are also susceptible to bit decay.

If you have the money your best options are to get a glass die made for imprinting either DVD's or CD's with the data you want, as this is an actual physical representation of your data. I also know that there is a company somewhere that will etch your binary data onto gold plates for the ultimate lifespan.

Tape backup is another time-tested solution except the readers and media can get expensive.

I personally use a device like this as because it stores the data with RAID 1, a mirror onto both hard-drives, so in case one fails, you can rebuild the data... and if both fail, the experts have twice the hard drives to retrieve data from.

Lastly, I would consider using a printed binary copy of your data. There is a “joke” (though functional) open-source project called PaperBack which includes such features as compression and redundancy that will allow you to print your data as 2D barcodes onto actual sheets of paper and store them in your safe.

The reason I mention all of these options is because lets say you store a flash drive in your safe, AND a burned cd AND a tape backup.. and your house burns down. The temperatures exposed to this safe will cause the flash drive, cd, tape, etc to melt and be useless (even with expert recovery people). Paper copies or etched glass will be more resilient to this type of damage.

Lastly I would put my data in the 'cloud', amazon offers data store with a free 5GB start I believe. Also a company called dropbox has a VERY convenient and cross platform syncing system with cloud storage starting free at 2GB

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  • Paper is more fire proof than plastic in metal? I find this hard to believe.
    – Skeith
    Commented Jun 16, 2011 at 9:47
  • A fireproof safe will keep the oxygen and fire out. Only the heat gets in (slowly). That means that paper in a fireproof safe would degrade through thermal dissociation; it won't catch fire and burn. And it's easy to believe that such degradation happens at higher temperatures than the melting of plastic. Many plastics are designed to melt, as it makes forming them a lot easier.
    – MSalters
    Commented Jun 16, 2011 at 11:09
  • Archive grade Gold CD-DVD's are a good choice also, multiple copies in multiple locations of course.
    – Moab
    Commented Jun 16, 2011 at 15:34
  • I would not rely on the ability to rescue magnetic media. As capacities have gone up, the redundancy of the signal has gone down - the heroic techniques of yesteryear to revive a disk are now part of the normal electronics, used for everyday operation.
    – Mark Ransom
    Commented Jun 16, 2011 at 18:16
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I agree with D.Iankov regarding changing the media every 10 years, or as you see that your current media appears to be aging compared to new technology, as well as the availability to be able to use the old technology, you would want to change it then.

As far as a current media, a flash drive, while very stable overall, they are still more subject to failure when compared to a DVD. I would use a DVD burner and put them on DVD. The estimates for DVD life vary greatly from 20 years to 200 years. If you store them in a cool dark location, I would think you would get at least 50 years out of a good quality disk, but again, you will need a reader in the future, and that may be tough to get in 50 years.

I also agree with keeping multiple copies in different locations if the data is extremely valuable. I have seen backups fail, and the only thing that saved the company was having multiple copies. I have also had a company (as a consultant) burn down, and they were not good about taking a tape off-site weekly, so they lost all their data.

http://www.audioholics.com/education/audio-formats-technology/cd-and-dvd-longevity-how-long-will-they-last

http://www.guardian.co.uk/technology/askjack/2008/may/08/howlongshouldadvdlast

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  • Upvoted. Although claiming 50-200 years of life, some of those DVDs I burned several years ago are already unreadable due to degradation.
    – Kromster
    Commented Jun 16, 2011 at 9:35
  • @Krom I have CDs that at 15 years old that work fine...never had one that did not.
    – KCotreau
    Commented Jun 16, 2011 at 10:14
  • The shelf life of DVD-ROM is not nearly the same as the shelf life of DVD-R. Even DVD-R and DVD-RW differ. You can't talk about the shelf life of DVD unqualified.
    – MSalters
    Commented Jun 16, 2011 at 11:03
  • @MSalters Please provide some links. I have never heard of these differences you talk about. Frankly, I do not believe they exist, but I am willing to admit you are right if you can provide links. I also did not talk about it unqualified. The estimates, and that is all you can do until years pass, vary widely, and are mostly determined by how well it is manufactured, and how you store it.
    – KCotreau
    Commented Jun 16, 2011 at 11:58
  • See en.wikipedia.org/wiki/… . DVD-ROM uses physical pits, which are nearly indestructible. I was partially serious when I mentioned chiseled rock in another comment. Physical storage is remarkably stable. DVD-R on the other hand uses dyes, which are by design unstable - you must be able to change them. High temperatures accelerate the process, which is how a drive works, but at room temperature the process doesn't stop.
    – MSalters
    Commented Jun 17, 2011 at 10:02
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Everybody has been very correct in pointing out that flash drives are very durable if stored correctly.

Then why am i posting yet another answer?

The reason is that no matter how good you store your flash drives, they will eventually need to be read, somewhere. Now that they are plugged in, they can be destroyed by a variety of causes. Sudden buildup of static electricity, poor power supply, logic failure, operating system failure, et cetera, et cetera.

Thus, remember, if you want to make sure you store it properly, make multiple copies, at multiple places, in multiple formats. I would have taken a master-grade CD (e.g. one from Taiyo-Yuden), a SD card, a USB drive, and/or something else, and put it in two different safes if it were so important to me.

Good luck!

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Paper is still the (easily created) format that holds up best over time. Properly stored paper can be read for thousands of years.

Any modern digital format should be refreshed frequently (with the value for frequently determined by the media type.) I would refresh any VERY important data at least annually and keep three copies in separate locations.

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  • but the recent paper is different from old papers and also the ink. we have to analyze that...
    – kokbira
    Commented Jun 16, 2011 at 18:02
  • Honestly, I don't encourage the use of paper to store data unless it has to last a very long time with minimal upkeep. (Like archiving knowledge for post apocalyptic reasons.) Even then you would need to verify the paper and ink/toner is acid free and will not break down too quickly AND locate a storage facility that is safe from flooding and geologically stable.
    – Chris Nava
    Commented Jun 17, 2011 at 14:01
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Print a hard copy, get it laminated, put it in the vault. It should still be there and readable in 100 years. Storage media and software codecs could become obsolete in 100 years, but I doubt that copiers or scanners will become obsolete anytime soon.

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  • A good quality print kept out of direct UV (behind glass is OK) will last a long time, longer if you keep it in the dark.
    – ChrisF
    Commented Jun 16, 2011 at 20:08

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