I would like to store a small amount of data (< 50 MB), in a durable way. Besides printing out on paper or engraving it, what is the most durable way?

The scenario I am thinking of is storing it for 10 years in a bank safe deposit box. Should I burn a cd or put it on a usb drive, or are there other (specialized) options? Also important is that my computer in 10-15 years must be able to use the device.

Burned CDs

They are out of the question in my opinion. They start to dissolve after a while (I have 10 year old burned CDs here... Unreadable. You can see through through some of them!)


What would work is using a ROM and flashing it with 50 MB. You could have a USB ROM flasher which you could just replace if it doesn't work anymore. ROMs are pretty sturdy. Nintendo games from 1985 still work perfectly. Even Atari 2600 games which are even older still work perfect. I suppose current ROMs yield the same stability.

Third thing is using a streamer to write the data on magnetic band. They seem to be pretty sturdy, at least as long as no magnetic discharge rips the data. But they have way too much space. Like tens of Gigabytes or even a Terabyte.

But one last tip: If you're going to keep it that long, you might as well put two or three copies there, just if, by chance, one dies.

USB Flash

I don't know how well it keeps up. Might be comparable to a ROM?

My opinion

The one I know that will keep up long is a ROM. If possible, I would use this. But magnetic band is very reliable and used everywhere.

For true durability you should

  1. use multiple formats, some or all of: print a copy, write it to a CD, and a DVD, and a tape, and a flash drive, and a spinning-disk drive, perhaps burn it into an PROM device...
  2. use archival grade media in all the above cases
  3. make sure you store each copy with enough error correction data added in case all the copies get partially damaged - i.e. use an archive format like par2
  4. test the copies after a period of time, once per year for instance, unless for some reason it needs to be stored for 10 years without being touched, and replace copies as needed
  5. while you are testing the copies, reassess the media used (technology will be marching on, new formats may be common and old ones dying completely in terms of inexpensively accessible devices being able to read them)
  • 1
    Extended on my answer a lot. + for using more than one format. – sinni800 Jul 4 '11 at 10:41

This is a standard problem. You have both media deterioration and "environment deterioration" to worry about. By the latter I mean the ability to find an operating environment that can read the data, even if the medium is sound.

Punched cards will last 100 years, but good luck finding a reader, or even a way to punch them. Punched paper tape is a little better -- so long as you don't use oiled paper tape (which disintegrates in 5-10 years) the tape is good for maybe 50 years (longer for mylar) and you can jury-rig a viable reader. The problem is finding a punch and the tape.

CD or DVD will PROBABLY last 10 years, and the ability to read it will PROBABLY exist in 10 years, but I wouldn't put any money on either in 20 years. USB drives I'm fundamentally suspicious of, and there's no great assurance that USB will even exist in 10 years.

Someone suggested (programmable) ROM, but it depends on what type. Some are fundamentally the same technology as USB drives and subject to flipped bits over time. A fusible link ROM (do they still exist?) is probably safest, but even they are subject to shorting out from "fingers" of metal crystallizing in the gaps (though not so much when not powered). Plus you'd still have to come up with some sort or reader. (The ROMs used in mass-produced games are mask-programmed and quite reliable, but it'll cost you thousands to produce just one unit that way.)

I've often thought that someone should offer an archival media service, based on writing to photo film (which we know how to make last 100 years), but I've never seen any such offerings (and photo film is going the way of the dodo anyway). Laser engraving on a metal surface would be good, I suppose.

I'd probably just write redundant copies on two-three different CD/DVD brands and go with that.

But frankly, most find that "precious" data is no longer that important after 10 years.

Store it on Amazon S3 in an easily-readable format (or if necessary store the specification for the format too). I believe that Amazon S3 offers 11 nines of data durability (ie 99.999999999% of data is not lost).

Amazon is a good choice because:

  • Amazon is unlikely to fail as a company
  • it becomes Amazon's problem to manage the lifecycle of the storage devices - they are likely to upgrade the storage medium without you even knowing, let alone needing to care
  • safety in numbers - Amazon are storing vital data for thousands of people/companies, so it is in their interests to do it right, and they can offer economies of scale - ie your data is likely to be written to multiple devices in multiple locations. Storing your data locally doesn't offer this kind of redundancy unless you happen to be a multinational or government.

The only problem is that you need a reliable way to store the access tokens/URLs required to allow you to find/modify the data. Depending on the nature of the information you are storing, you may want to make this public (ie in the public domain and therefore known and shared by lots of people) or email them to yourself and trusted associates, or print them out/engrave it, etc. The good thing is that this information is very small and therefore cheap to 'immortalize'.

Disclaimer: I don't work for Amazon, but do store some of my personal data with them. I have never had a problem.

Keep it as part of your live data: You don't know if that CD/Tape/HD/USB Stick/Whatever sitting on the shelf still works unless you test it regularly. As your archives grow, the amount of time you spend testing media increases. However, you can be notified immediately if a HD in a RAID array goes south, giving you time to recover before you have to restore from backup.

Back it up regularly: If you have a catastrophe, you want to know that you can get it all back.

Keep the backup offline when not being used: That USB HD you keep plugged in all the time isn't much good if a virus wipes all your storage out, you fat finger a delete command, or a power surge blows everything that's plugged in.

Have multiple backups in different places: If your house burns down, gets blown away by a tornado, or drowned in a flood, you don't want all your backups in the same house as your data. Distribute geographically based upon your actual needs. Your parents (or kids, depending on your/their ages) or siblings or other relatives in a nearby town (or the next state) may be good enough. Never underestimate the bandwidth of a 2 TB HD sent via FedEx. :-) Spending $$$$ to store everything in datacenters on multiple contents is probably foolish though -- if a major disaster destroys everything in a 50 mile radius of your house, were your photos that important? Maybe some are, along with financial info, or other highly valuable data, in which case it makes sense to keep some of that data stored somewhere very remote at a reasonable cost.

Make sure your backups work: Test restores. It doesn't do you much good to have a backup if the media fails, or the reader fails, or you can't connect it to anything.

If you're worried about bit-rot, keep parity data of some kind (like par2, or rar w/ recovery records, etc.).

Migrate data and data formats as necessary: Hunting down the hardware to connect a 30 MB MFM HD is hard enough. Having it work is a small miracle. Now you've got to come up with a way to uncompress the files that are in some long lost boutique archive format. (Or maybe an ancient version of PK-ZIP, in which case you're lucky.) And now, extracting the usable data from that file format. If you're lucky it's from a major program, like WordStar, or Lotus 1-2-3. If you're unlucky, it's from some software company whose products have long since been lost in the mists of time.

Send an e-mail to yourself with the data, split it up if you have to.

Edit: Send it from one account to another, so that both would need to disappear to lose your data. In addition, you can forward it to any number of accounts every time a provider is going to disappear.

  • Implying that the E-Mail service will keep the file for 10 years. This happens, yeah, but I won't RELY on it. You will also have to have a contract for 10 years. If it's a free service they could just delete it. – sinni800 Jul 4 '11 at 10:38
  • They do give warning, so just forward it. – soandos Jul 4 '11 at 10:40
  • Remember when Google Mail accounts were accidently emptied once? Big time. – sinni800 Jul 4 '11 at 10:41
  • see edit. Would take two really low probability events occurring very close to each other. – soandos Jul 4 '11 at 10:42
  • 1
    Or you could just encrypt it yourself, and store the source code for some open source archiver that could do it in the media (guaranteed portability even 10 years down the line). – soandos Jul 4 '11 at 10:50

I would say "the most durable" is a hard drive (the mean time between failure for a quality drive is very high, which means it should last for many years, especially if not in constant use), but my choice would be to put it on a CD\DVD, which should last 10 years easily, but they can ultimately degrade eventually. Estimates vary, but 10 years should be fine if they are stored in a cool dark area. If you did choose a hard drive, and your hard drive failed, the data still likely would be recoverable on the platters by a data recovery firm, but that is expensive.

I would also choose CD\DVD's over a USB drive. They rarely fail, but I see USB flash drives die all the time. You could store your data for 10 years, plug the device in, and have it fail right there...not likely, but possible.

The key is multiple copies in different locations, and to test it from time to time. I have had clients think they had backups, but they did not test them, they had no redundancy (no multiple copies), and they failed. I had one client, whose building burned down...the backups were never taken off site. I had recommended an on-line solution, but it was expensive then, and they were too cheap.

  • 1
    you sure CD/DVD readers will be around then? – soandos Jul 4 '11 at 11:02
  • @soandos Probably, but even so, you have to use a little common sense if they look like they will be phased out, and copy to a new media. David Spillett correctly did point this possibility out. – KCotreau Jul 4 '11 at 11:05

store it on the internet ! :) the Datacenter in charge will take care of everything.

  • 3
    Famous last words. – efotinis Jul 6 '11 at 14:06

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