DVD Backup - Follow-up

It's simultaneously wondrous and frustrating, how often I publish the "latest word" on a technology, only to read the next morning that it's been superseded. Which is now the case with the future of rewritable DVDs that we discussed last issue.

Brought to our attention by reader Sander Olson, the Oct. 18 EE Times describes how Matsushita has announced a new, backwards-compatible version of DVD technology that can rewrite -- not the 4.7 gigabytes that is common today -- but 100 gigabytes on a single dual-layer, dual-sided disk! (They use new violet lasers which have a shorter wavelength than the ones in use today; that allows them to focus on smaller "spots," and so pack significantly more data onto a same-sized disk.) Wouldn't 100 gigabyte disks be a nicely-sized backup medium for today's tens-of-gigabytes hard disks?

There's another element of Matsushita's new DVD technology that would help the backup process. Last night, my PC's backup program (Retrospect) backed up 16 gigabytes of data from my hard disk to my tape drive at the respectable speed of 60 megabytes/minute. The problem is that since the backup program has to first write the data, and then go back and do another pass on the tape to verify that the data on the tape actually matches the data on the disk (that's the all-important "read-after-write verification pass"), the entire process takes about 9 hours. As my disk continues to fill up, not only will I need larger tapes (or an automated tape changer), but the backups simply won't complete overnight.

This new DVD technology, though, may be just what the data doctor ordered. Matsushita has demonstrated that their drive can record and play back data at 248 megabytes/minute, or four times faster than my current tape drive! At essentially one gigabyte every four minutes, this new DVD technology could theoretically (if the PC can feed it data fast enough) back up and then verify my entire 16 gigabytes of data in a mere two hours!

Much as I'd like to run out and buy one of these fast 100 gigabyte rewritable DVD drives today, they're a long way from the store shelves. There are compatibility issues with current DVDs, and intellectual property issues that have yet to be resolved. But the fact that this technology has now been demonstrated, and the value that such large and fast rewritable storage media would bring, make me confident that this or a similar technology will find its way into our homes and offices.

(By the way, on the more expansive issue of "data preservation" that we also discussed last issue, reader Michael Bruce points out that there are companies who offer solutions to this very issue. One such company he brings to our attention is Kodak, which offers an explanation of the problem, including some chilling examples. Such as the corporate data of the Pennsylvania Railroad being completely erased. Or that 20% of the 1976 Viking Mars Mission data no longer being readable...)

I just hope that these "bigger, faster" DVDs roll out soon -- before our hard disks grow so much larger, again, that a "mere" 100 gigabytes of backup capacity will not be nearly enough...

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