In the early days of PCs, the only backup option was floppy disks, and using them was a time-consuming and clumsy affair. Even with skillful use of a specialized program such as FastBack, the best backup speed you could hope for was about a megabyte a minute. Once hard-drive sizes exceeded what reasonably could be backed up in about the space of a coffee break, 20 Mbytes or so, floppies ceased to be a practical backup medium, and tape drives became de rigueur.

Tape backups are still in wide use today, and they're OK. Not great, just OK. High-capacity tape systems, especially centralized, server-based "juke-box" arrays that can back up arbitrarily large quantities of data, are quite expensive. Lower-end systems can be slow and noisy and, with limited capacity, require a human operator to serially load new tapes as needed. Plus, all tape-based systems require special hardware (the tape drive), which limits backup/restore operations to the PC(s) on which a tape drive is installed or is accessible.

Worse, blank tapes are relatively expensive, so long-term storage for large amounts of data becomes a very pricey prospect. To avoid huge investments in a static tape library, many enterprises and individuals who use tape simply forgo long-term storage. Instead, they recycle the same tapes over and over, a practice that largely negates the archival benefits of making backups in the first place.

Tape's Worst Problem
Those who use tape for long-term data storage face another problem. Tapes don't age gracefully. There can be problems with stretching or embrittlement of the plastic backing; problems with the adhesive that holds the oxide coating in place; problems with the oxide itself losing signal strength through self-demagnetization over time, or from being affected by stray magnetic fields from external sources; problems with dirt and dust; and even problems with the rollers and guide pulleys.

Without some kind of carefully climate-controlled storage area and high-quality, professional-level caretaking, I wouldn't want to trust irreplaceable data to tapes for more than a couple years, at best.

Of course, some records and files only need to be kept for a few years, well within tape's lifetime. But in the United States, the general legal statute of limitations is still seven years. That means any records that could be needed for legal disputes must be archived for at least that long. Other items, ranging from patent, copyright, and corporate historical records to family photos and digital videos, might require a much longer shelf life, reaching decades or even generations. Tapes just aren't up to these tasks.