subject: Long Term Data Storage - The Options [print this page] I've had a few people ask me just recently what method I would recommend when planning a long term backup strategy. One elderly gentleman in particular was creating a family time capsule that he wanted his children and grandchildren to be able to view many decades from now.
The question isn't as easy as you may think. You may imagine that the data could be burnt to CD, locked in a cupboard and that it would last forever however unfortunately this isn't the case. There are literally hundreds of suitably stored but physically decayed CD's from my teenage years which I could use as testament to that.
Due to these considerations, I've made a list of formats that you might consider using for long term data storage so that you can pick the one most suitable for your own needs.
Hard Disk - When used on a regular basis a hard disk will typically last for around 5 years before it starts to decay and if it is being used as an infrequently accessed backup drive then we can assume that this can be at least doubled. Unfortunately degradation of the discs metallic surface, along with the inevitable seizing of parts would still occur over an extended period of disuse.
Optical - Optical media can include DVD, CD and BluRay. It is important that if choosing this type of media that you go for the higest grade you can obtain; a premium brand such as Taiyo Yuden may last 10 years but a more budget brand may only last half that time. When the disc begins to degrade the aluminium will actually start seperating from the plastic.
Flash Media - Clearly you would expect that since Flash Media has no moving parts it would be ideal for a long term backup strategy. To an extent you would be right but the published data retention of a unused flash drive is only around 10 years and unfortunately once the device has reached the end of its life it is likely that it will go out in style, taking with it all of the information stored within.
Paper - Rather obvious this one - if left in a dark, dry place then paper will last for many decades; we recently recovered a number of newspapers from 1964 from below the flooring of a building we're doing up and aside from being a little yellowed they're in perfect condition. Primary problems do of course include having to find a safe place to store them along with the physical limitations relating to the amount and type of information that can be stored on sheets of paper.
Tape - You wouldn't have necessarily thought it but the humble tape has one of the best data rates available. With typical warranties lasting around 30 years with a life expectancy beyond that it's little wonder they continue to be used in banking and government sectors.
The primary downside is that although the tapes themselves are affordable and the capacities typically high (up to 1TB is relatively normal) the actual drives themselves are usually expensive.
Solid State Drive - Using a similar technology to a flash drive, an SSD is usually used as a direct alternative to a hard drive. Usually used in notebooks, they unfortunately suffer the same problems as flash in that their data retention should only be considered to be around 10 years.
The Internet - Theoretically one of the most robust ways of backing up data, an online Internet server is typically backed up daily, monitored 24/7 and if a problem does occur with the hard drive containing your data a mirrored backup drive would take over with no down time.
If you were looking to store the data within your own lifetime the Internet would be a perfect storage medium however if looking to preserve the data for future generations then this method has some major flaws. For exameple, if you store your data on a free online storage account then the company either goes under or starts charging for the service then your data would be lost.
Magneto Optical - Although it is certainly a niche product, Magneto Optical might be your best solution if long term data storage is your goal. Originally introduced in the 1980's, MO drives are slow and currently have a maximum capacity of just 9.1GB however with their slow speed comes a ruggedness that allows manufacturers to provide their discs with a 100 year data retention claim, often with a warranty to match. High end drives are expensive but you could enter the market with a 1.3GB drive for around 100.
Of course, when devising a long term archival strategy we assume that hardware will be available at the time that it needs to be played back. This is a serious consideration when we're talking about storing the data for best part of a century but in our own lifetime it won't necessarily be a problem - the first video camera my family owned used the 8mm Video8 cassette tapes and although 20 years down the line I don't own a compatible reader, I could obtain one if necessary.
Another good tactic is to also keep several copies of your data on several different media types and store them in different locations. Although it acts as no guarantee, it increases the chance that one will survive the test of time.
If possibly check on the media every few years and transfer it to newer, more suitable media types as and when they become available.
