Long Term Data Retention

Can you assume that your computer data will be safe and accessible for as long as you need it to be?

How should we store our important computerised data so as to be reasonably sure that it will be available to us for us long as we need it? Is there any electronic format that we are sure will do the job? I’m not sure that there is an obvious answer to this question.

Part of the personal computing revolution
at the beginning of the 1980’s included the ability to store programs and data on magnetic media in the form of the floppy disc. This was a circular disc that rotated inside a protective, semi-flexible (ie “floppy”), sleeve. I think there were discs measuring about 8 inches across at one time. When I got into the field in 1983 the current size was a 5 1/4 inch disc. These contained about 1/3mb of data.

I’m fairly sure that I’ve still got a drive to read these discs somewhere, but I’ve got no idea whether that drive is still compatible with modern computers. If I couldn’t read the disc myself then I would do some googling in the hope of finding a company specialised in reading old media formats. This would probably be expensive and I don’t know what the chances are that the discs themselves would still be readable – even if the “reader” were available and working.

So, if I’d written the greatest novel of the 20th century, stored it on 5 1/4 inch discs, and then forgotten about it, I may or may not be able to read the disc (and may or may not have a program capable of interpreting the data even if the disc itself were readable, but that’s a different story).

Scrunched Floppies
A client asked me to render these old 3 1/2 inch floppies unreadable by pulling out the discs and scrunching them up
The media that took over from the 5 1/4 inch floppy was the 3.5 inch version. This time the case was rigid and the capacity had increased about fourfold. If you have a computer that’s older than about five years then it may have a drive that can read/write these discs but the chances are that if you still actually use it then it will probably be because you have an old accounts package that wants to do data backups onto floppies (accounts data doesn’t take up much room, so it is still quite feasible to do this).

If you put the greatest novel of the 20th century onto 3.5 inch discs then you wouldn’t have a problem accessing it as you can still buy external 3.5 inch floppy drives that connect via a familiar USB interface. If the discs have been kept in a reasonable environment then you can probably still read them. You couldn’t use floppies for most of today’s data storage requirements as they just aren’t big enough.

You might expect that any storage discs newer than floppies would be straightforward as these would be CDs or DVDs. Again, if your computer doesn’t have a drive to read/write these then you could attach an external one.

Disintegrating CDs
You can see the coating starting to come off at the edge of these CDs
No problem there, then, but it’s not just the survivability of the drive to read the media that we need to worry about. It’s also the media itself. I recently dug out an oldish music CD that was disintegrating from the edge (see the illustration). OK, it wasn’t a proprietory disc (so the legality of the copy is somewhat challenged), but my point is that I don’t think the disc is more than about 10 years old. Another short while and the disintegration will have worked its way onto the data area and the disc will be useless. Is this going to happen to all CDs? Maybe I was just unlucky. Maybe the CD was cheap. The point is that the disc could have contained important stuff and that stuff would be at risk.

Where else can you put your data for long term safety?
Hard drives seem like a good bet at first sight. However, I recently dug out a pile of redundant hard drives that I thought were in perfect working order and two out of four refused to start up. Is this typical of what happens to a drive if it isn’t used? I don’t know, but I certainly won’t be trusting a unique copy of anything important to a single drive.

What about pen drives (aka thumb drives, USB drives, or (erroneously) “memory sticks”)? It’s possible that these fare better in the long term. After all, there are no moving parts. You can now buy these with capacities of 64gb. That’s usually plenty big enough to store all your important text data, if not photographs and music.

Pile of Hard Drives
Old hard drives may not “spin up” if not used for a long time
But maybe the safest bet is to commit your data to an online cloud storage service. I would still feel a bit queasy about putting all my eggs in one cloud basket (as it were), so would replicate the storage in two different services (eg Microsoft’s SkyDrive and Apple’s iCloud). It may not yet be practical to do this if you have lots of data as online storage costs money for large storage amounts. Nevertheless, this situation is bound to improve as storage continues to become cheaper and data transfer speeds continue to rise.

So, there doesn’t seem to be a single, obvious solution at the moment and I’ve got a lot of sympathy for all those people who only really feel safe with their data storage if they’ve got a hard copy on good old paper (which, itself, disintegrates in time of course). For my own stuff, I think I’ll continue spreading my backups around between hard drives, CDs, DVDs, pen drives, and keeping some of my old stuff handy in Dropbox etc.

And I always, always, have at least two archive copies of anything important.