My 5/26/08 Missoulian column
I touched on the preservation of digital files a few weeks ago, and since then I thought I’d go deeper into the subject because it will continue to be an issue for years to come. Digital technologies are still emerging, with more change to come for at least another generation. But we need to have more than passing concern about preserving digital files – valuable photos, tax returns, important documents, e-mail – for the future.
What most of us know, of course, is there has been a huge shift in information usage and storage in the past 20 years. Think about typewriters, cassette tape decks and record players – all “analog” devices that were popular at yard sales just a few years back, but are now difficult to find. Almost everyone now knows we’re in a brave new digital world with personal computers on our desks, iPods in our pockets and digital TVs in our living rooms.
I think there’s less of a realization that the means of preserving files is different than in the old days. What used to be photographic negatives and prints, books, letters, papers, cassette tapes and LPs – all items that could, for the most part, be tossed in a box and forgotten to preserve – are now files on a computer. You might only become aware of this when the files you have on an old disk are suddenly “gone” because it’s no longer compatible with your new PC.
There are two main aspects to file preservation that are the same in both the analog and digital worlds: content and media. And with digital files, there’s a third: file formats, which I’ll talk about next week.
With cassettes, for example, the content is music – represented as faint magnetic fields – and the medium is the plastic tape. On LPs, the musical content is represented by tiny bumps pressed into the record’s grooves, while the disc itself is the medium. In the digital world, the content is stored as a physical representation of ones and zeros in the microscopic indentations on a CD; magnetically on a drive; or through a minute electrical charge on a solid-state memory chip.
Something that hasn’t changed is that both analog and digital technologies require a device to read the media. Record and tape players are still available because they were manufactured in large numbers and in use for more than a few years. Digital technology has been changing faster than analog ever did, likely a result of the amount of money involved in the high-tech businesses that drive innovation, and equipment becomes orphaned quickly.
What people have found – and what some businesses have sprung up to take care of – is that whole computer systems sometimes must be maintained to use an old medium that’s no longer manufactured. Different drives must be kept around for disks that turn up and need to be read or transferred to newer technologies.
What about the life span of different kinds of disks? Floppy disks are too unreliable and really aren’t in circulation anymore. Hard drives have become extremely reliable, but they still crash. Flash drives are solid state – with no moving parts – but the odd electronic glitch (sometimes caused by naturally occurring background radiation) can flip a few digital bits and render them either partially or fully unreadable.
What about CDs? Store-bought CDs are manufactured by pressing tiny pits into the reflective surface under the clear plastic of the disk. The pits are read by a laser that then translates them into music. This gives manufactured CDs a long life span – 50 to 75 years – because they have no moving parts and are a passive way of storing information.
Recordable and rewritable CDs (CD-Rs and CD-RWs), on the other hand, are “burned” with a laser that etches dye inside the plastic. These dyes have a limited life of sometimes only a few years, and because these are the only types of CDs that can be made on a home PC, users should be wary of storing important files on them for the long term. You can read a white paper on the life span of CDs from the Information Technology Laboratory of the National Institute of Standards and Technology.
So, what is one to do? Be aware of what you have on your hard drive and CD-Rs, and decide if the information is as valuable as it would be if it was an old-fashioned hard copy.
Don’t store files for the long term on CD-Rs. Hard drives are currently the best choice, and USB drives are reliable and cheap. I think USB technology will be around for years, and can safely be used for long-term storage. Sometime in the future, solid-state drives will become more commonplace and may replace many other forms of storage, but that’s down the road.
The best long-term file preservation solution is to make copies on several USB drives. Tear a page in a book and you can tape it back together; break a cassette tape and it can be spliced. Do something analogous to a hard drive and the pages are gone, as well as possibly the whole book.
If you already have valuable files on old floppy disks or hard drives, ask a local computer shop for help transferring them to a newer drive or look to Google for businesses that can rescue files.
The other issue with long-term digital file preservation is the format of the files. All digital files – such as word processing documents, images and more – are saved to a disk in a particular structure that may or may not be readable in the future. I’ll explain that next week.