Was doing so well
This started out as a great, well-balanced article. Even had comments and clarifications such as: "But disk, constantly online disk, is always at risk....", note the "constantly online disk" clarification.
Then, disregarding all this preamble, Chris writes his conclusion thus:
"Tape's cost/GB stored blows disk away. Tape's reliability, with today's media and pre-emptive media integrity-checking library software is far higher than disk. Tape cartridges don't crash. Tape cartridges aren't spinning all the time, drawing electricity constantly, vibrating themselves slowly to death, generating heat that has to be chilled, and – most importantly – are not always online, always susceptible to lightning-quick data over-writing by dud data or file deletion."
He again compares to tape and states "and – most importantly – are not always online" (which is a good half the paragraph of the effects of disks being always online). He also assumes that the pre-emptive media integrity-checking is a common feature, rather than the new (old?) idea that just got implemented in a single tape library from a specific vendor....
Also, once again, he assumes "Tape's cost/GB stored blows disk away." which, in fact, it doesn't. A "FUJIFILM LTO Ultrium G5 - LTO Ultrium 5 - 1.5 TB / 3 TB" (from Amazon) lands at $67USD, being one of the cheaper options, but you can get a "Seagate Barracuda 7200 1.5 TB 7200RPM SATA 3Gb/s" (from Amazon) for $69.99USD (regardless of how you feel about Seagate. You want WD? It's only $64.99 atm). That's bit for bit the same size (the 3TB is assuming a 2:1 compression, which can be done using HDDs as well. The effective bits are the same, 1.5TB). Sorry Chris, cost evaluations are required before claiming a cost difference that "blows disk away."
As for longevity, I'm willing to bet disk has a higher in-use lifespan too. Have a tape that has as many on-hours as an HDD, and tape will lose. Granted, this has no relevance since most backup storage is used perhaps 30 times before being permanently archived/retired.
When you're looking at solutions such as "Overland Storage REO 9100C VTL" or the equivalent Tape variety, you're definitely going to do better with the traditional tape option, due to the always-on disks and the like, but use a JBOD disk-spanning option, and you could take your backup targets offline (the disks) once your backup job is complete (referring to the last D in a D2D2D option).
Disks have pros and cons compared to tapes, but currently, it's more of a user-preference than any technical or "better than" mythos that delineates the use of either.