So they’re finally getting around to testing digital recordable media:

PCWorld.com - Burning Questions: When Good Discs Go Bad

“We’ve found the quality varies, depending upon the type of dye used to make the write-once discs and [on the] the manufacturer,” reports Byers. Even discs from the same manufacturer, with the same brand, can test differently, Byers adds. “But there was more of a significant difference when you compared discs between manufacturers,” he explains.

But this news is even more discouraging:

“One thing we’ve found in compatibility testing [of DVD-R and +R media] is that it’s a relationship between a specific brand of media and the manufacturer of the hardware,” observes Byers. “There was no one drive that played every single type of compatible media, and there was no one media brand that played perfectly in every drive.”

And, he adds, sounding as frustrated as any consumer might, “You can’t say there’s a clear, delineated set of reasons as to why.”

Reminds me of floppy drives, which had alignment issues that could often prevent disks written on one drive from being readable on another.

Tape is still a reliable form of long term storage, but tape drives (and/or tapes!) are still very expensive. I’m beginning to think that the best method of backups these days is a big JBOD(Just a Bunch Of Disks) or RAID(Redundant Array of Independent Disks) server; hard disks are reliable…

Update from 2025: The backup server now has four 16-TB drives in two RAID-1 mirrors. Plus ce change…