[... about DVDs vs. HDs...]
I quite appreciate the 2 HDs setup (one internal, on-line, one external,
only connected for back-ups), as it is rather safe (I take quite drastic
precautions, see below) and very convenient (I always have ALL images
on-line).
Both disks should get full far before they reach their MTBF, I'll
replace them for disks 3x their sizes, and migrate their contents to the
new units... This solves the redundancy issue, the media refreshing
issue, the increasing data volume issue, all at once, and at a low cost
(HD GigaByte is much cheaper than DVD GigaByte)... And I still burn best
images to DVDs/CDs just to be on the safe side with 3 independent copies
or more.
[Detail of precautions taken...]
The two disks are bought from different stores, of different brands.
External disk is never plugged to the same PC as the internal disk, and
only during backup procedures. Its on-time amounts to mere minutes.
Between backups, external disk is stored at my office, 30 kms from here.
When possible, I transfer files to be backed up between the 2 disks
through my office's laptop, so the two disks are never connected to the
same power network.
Both disks are monitored by smartmontools on a regular basis.
