CyberDyneSystems wrote in post #11081855
...With terabytes of information, it is simply not reasonable to USE CDR anymore,. and hasn't been for a long time. EVEN DVD-R is too small IMHO....
That's true, but the archival CD-R is still the best long-term storage media for digital data, with a claimed life of 300 years. That same manufacturer claims to have archival BD-Rs (blue ray) with a life of 200 years, longer than they claim for their DVD-Rs (100 years).
If all you are archiving is your original raw images, a CD-R can hold approximately a "roll" of photos (30 - 35 shots) whereas a BD-R can hold about 1000 shots. This is getting more reasonable for backing up a job using BD-Rs.
However, we're facing the same issue the Hollywood studios face with digital ... an explosion of data.
Ansel Adams archived his original negatives and notes on how he made each print. Color photographers would archive B&W separation negatives to preserve the color. Life is not so simple anymore.
Since each incremental image is essentially "free", the number of images taken per event, job, or even family outing is many times greater than it used to be with film. In addition, we no longer have a notebook of darkroom notes, but instead all kinds of work files, depending on how we post-process the raw images. We may want to keep the photoshop files, perhaps multiple files of steps along the way, but we may also want to keep a copy of the final work product.
A RAID array is a reasonable way to keep an archive always fresh, since if a drive fails, when that drive is replaced, the archive is written new to the replacement drive. But, you still need some way to keep a copy of the archive off-site. Perhaps the "cloud" can help, with services like Mozy, but do not trust these kinds of services if all you are using is their cheap "home" backup service. My experience is they have about a 99.9% recovery integrity rate, but that 0.1% that cannot be recovered is worrisome. If your archive is critical, use a commercial service, not the $5 per month "unlimited" home service.
But, I still like to have my valuable data on an archived copy that is "write once and store" and does not require anything to be powered up and does not require that I trust anyone else's equipment to be powered up and reliable. Double-layer blue ray is now up to ~50 GB per disk, but I don't know if anyone is making "archival" version of that, yet. Manufacturers are working on 100GB-400GB blue ray discs now (up to 16 layers).