Okay, let’s get started. People occasionally ask me what techniques I recommend for archiving images. I tell them that I don’t recommend archiving images at all, but I strongly recommend backing them up. Let me explain the difference.
When you create an archive of an image, you make a copy of that image that you think is going to last a long time. You store the archived image in a safe place or several safe places and erase it from your hard drive. That’s called offline storage, as opposed on online storage, which stores the data on your computer or on some networked computer that you can access easily. If you want the image at some point in the future, you retrieve one of your archived images, load it onto your computer, and go on from there.
When you back up an image, you leave the image on your hard drive and make copy of that image on some media that you can get at if your hard drive fails. Since the image is still on your hard drive, your normal access to the image is through that hard drive; you only need the backup if your hard drive (or computer, if you haven’t taken precautions) fails.
The key differentiation between the two approaches is that with archiving, you normally expect to access the image from the archived media, as opposed to only using the offline media in an emergency. A world of difference stems from this simple distinction.
I’m down on archiving for the following reasons:
Media life uncertainty. It is difficult – verging on impossible – to obtain trustworthy information on the average useful life of data stored on various media. Accelerating aging of media is a hugely inexact undertaking. Manufacturers routinely change their processes without informing their customers. The people with the best information usually have the biggest incentive to skew the results.
Media variations. Because of manufacturing and storage variations (CD or DVD life depends on the chemical and physical characteristics of the cases they are stored in, as well as temperature and humidity), you can’t be sure that one particular image on one particular archive will be readable when you need it.
File format evanescence. File formats come and go, and by the time you need to get at an image you may not have a program that can read that image’s file format.
Media evanescence. Media types come and go (remember 9-track magnetic tape, 3M cartridges, 8-inch floppies, magneto-optical disks, the old Syquest and Iomega drives?). By the time you need to get at an image you may not have a device that can read your media.
Inconvenient access. You may have a hard time finding the image you’re looking for amidst a pile of old disks or tapes.
Difficulty editing. Over time, your conception of an image worth keeping probably will change. But it’s a lot of trouble to load your archived images onto your computer, decide which ones you really want, and create new archives, so you probably won’t do that. You’ll just let the media pile up. Your biographers will love you for that, but it will make it harder to find a place to store the archives, and harder to find things when you need to.