Anyone archiving using Blu-ray disks? I like to keep back-up copies of all my stuff (incl. all my .flac files from my CD collection) in TWO different off-site locations, so this is something I'm looking at. I know HDs are dirt cheap right now, but don't optical disks have some advantages for archiving?
I haven't even considered using Blu-ray for storage yet, simply because the cost of the media is so high that its benefits compared to DVD+R are negligible.
There are several schools of thought regarding media reliability. Here is a brief (and therefore incomplete and inaccurate) list of pros and cons when used for backup copies:
Harddisks:
+ high to very high capacity
+ fast
+ cheap
+ good at random access
- moving parts
- sensitive to electromagnetic fields
- sensitive to moisture and dust
Flash-based media (current solid state disks, CF cards, etc):
+ medium to high capacity
+ fast to very fast
+ no moving parts
+ some media are exceptionally robust against moisture and dust
+ very good at random access
- sensitive to electromagnetic fields
- unproven in terms of long-term reliability
- expensive
Tapes:
+ medium to high capacity
+ proven in terms of reliability (some technologies are bad, though)
- moving parts
- sensitive to electromagnetic fields
- medium expensive
- bad for random access
Optical disks (CD, DVD, Blu-ray):
+ resistant to electromagnetic fields
+ potentially very good reliability and long term properties
+ no moving parts (but spins when in the reader/writer)
- very low or low capacity
- may be sensitive to air pollutants
- some choices of chemical dyes lead to media degradation
- sensitive to light
- sensitive to scratches
I've posted quite a bit about backup strategies before, and I still think that keeping data on different kinds of media, as well as migrating to new copies every few years, is a good strategy for securing the data.