when archiving on DVD, should i make a mirror copy similar to RAID 1?

I would like to archive photos. Hard drive (HD) are unreliable after 3-5 years and are not design for long-term storage. DVDs are much better.

From my research i found that TAIYO YUDEN dvd+r is the best option and should last decades. I would like to delete photos off my hard drive and have them on DVD. I like multiple back ups but would like to eliminate HD to save space. I plan to have a dvds at home and a copy at work, also i'd keep a copy on adrive.com (cheap i-net storage).

so i've made identical dvds and stored them in different places. with time dvds will get bad sectors; most likely in different places. i'd like to combine the images of these old dvds with bad sectors to get one good image. similar to mirroring hds with RAID 1.

i'd like to know if there is a program that would combine 2 or more .iso files that have errors and get one without errors.

any suggestions on better archiving options are appreciated.

Answer

dd_rescue

Automatic merging of backups: If you have two or more damaged copies of a file, cdrom, etc, and run ddrescue on all of them, one at a time, with the same output file, you will probably obtain a complete and error-free file. This is so because the probability of having damaged areas at the same places on different input files is very low. Using the logfile, only the needed blocks are read from the second and successive copies.

the program clones the possibly damaged images. while cloning, it notes bad sectors in a log file. when 2 or more of the cloned images and the log files are combined, the bad sectors are replaced by good sectors.

Note: for compressing files, there is lzip. it is based on lzma but with added rescue features (Lziprecover) it is also works with dd_rescue.