I'm considering Blue Ray disks as a "physical" archival media. Is this a good idea, and if so, what is the best disk to buy?
I'll also have tape for the magnetic back-up, but feel better having both.
Good idea? Not really.
Blu-ray is not really a superior technology compared to DVD. The only reason Blu-ray "won" the short-lived HD format war was because Sony bribed the studios. Yes, Sony paid companies like Warner Brothers to adopt Blu-ray and dump HD-DVD. Depending on which report you read, the Warner deal was either $400 million or $500 million. It had NOTHING to do with the tech itself.
It's a tech nobody really asked for:
Blu-ray suffers from a few major issues:
- Most people can't tell the difference between a DVD stretched to fill a screen, and the HD version -- especially on those tiny 30-40" screens. You really can't see HD until you get well into the 50-60" range and larger.
- In terms of data size, 25GB/50GB per discs isn't very much. Yeah, great, a half-dozen or dozen DVDs -- big deal. The cost of the BD-R and time required to burn isn't much fun either.
- The data grooves are microscopic, narrower than the already-problematic widths found on DVD. Why does this matter?
- Slight scratches -- including scratches invisible to the naked eye -- can cause large areas to become unreadable.
- The disc must be perfectly balanced to play correctly. Any warping due to storage or age could have long-term affects on readability in a few years. As with DVDs, any label could ruin a disc.
- Errors on a video disc play with visual/audible errors -- it just skips through the problem and keeps going as best it can. Data halts and can be destroyed/unreadable. This is true to any optical media, but worse on BD-R.
- The discs hovers just a few millimeters off the laser/reader assembly. Why does this matter?
- It's not uncommon for the disc to be scratched during normal use. And scratches can cause problems. (Note that Blu-ray media includes an anti-scratch costing, but that will still wear over time.)
- Weakening lasers give out faster compared to DVD players/readers. While this won't mean a lot during the burning process, reading the data back at a later time could be an issue. As lasers age, its strength and the ability to focus diminishes.
- Much like recordable DVD media, the longevity of the second layer is suspect. Unlike single-layer recordable/pressed media or pressed dual-layer discs, the technology used for dual/double-layer recording is new. There were many problems that caused the technology to almost not exist (in 2003 even optical engineers said it would never happen!), and those same issues could affect longevity.
If you still insist on using BD-R for archiving, stick to the same quality brands/manufacturers from CD-R and DVD-R. Namely Mitsubishi / Verbatim. Look at the media available at:
You would do best to archive data to hard drives (one on-site, and one off-site). Your "off-site" can be at the office, at the home of a parent or family member, etc. Just anywhere different that would not be affected by one natural disaster. (Your neighbor's house, for example, is a terrible off-site location.)
And then create secondary backups to single-layer DVD media for the most important data. At only 4GB per disc, in a GB-hungry age, this can be tedious. For that reason, cherry-pick what is important, and save the "I want to back it all up" method for the drives.
Contrary to some myths, backup tape is pretty terrible. DAT tapes, for example, are notorious for failures. A tape is easy to "eat" by a device, but it's much harder to damage a well-stored optical disc (CD/DVD) or hard drive by comparison. Optical and magnetic disks are also less damaged by humidity, compared to tapes. A tape is the really the only storage format that is put in danger every time it is played or accessed, essentially having it's guts accessed by a foreign object. A hard drive is enclosed, and a disc is read by a laser -- nothing invades the media to access the content, or to write content.
On the DVDs, only use the best blank discs
-- listed at http://www.digitalfaq.com/guides/media
-- and store then carefully. I suggest jewel cases in a box, for archival backups. Not wallets (scratches), not spindles (scratches), not movie-style cases (warps). Beyond that, make 2-3 copies, on various discs. For example, a Taiyo Yuden DVD+R, and a Verbatim/Mitsubishi DVD-R, with one set stored at an off-site.
Every 5-10 years, transfer to new media. (And keep the old version, if the media is still good. More copies!) I just recently started a project of archiving CD-ROM, CD-R and DVD-R/DVD+R to hard drives as ISO files. Long, long project. That hard drive will then be duped, and the copy stored at a family member's house 700 miles away.
You never realize how important data is until you've lost it!
Choosing a good method is key to success.