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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.

kirill_igum
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6 Answers6

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The best backup/archive policy is 3 copies: 1 primary, 1 backup in case the primary fails, and 1 off-site in case of a fire or such.

Ignacio Vazquez-Abrams
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The best method I've heard for backing up data is the 3-2-1 method. That is: three copies of the data, two media types and one off-site.

uSlackr
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The reason why RAID 1 works is because, in the event of a read failure, the other drive is consulted. The drive with "good" data is determined by which one failed to read. If a drive is corrupted in-place (i.e. when not in use) and subsequently read, then conceptually there is an ambiguity over which drive is right.

If I needed to use DVDs, I would do what you're doing and make three (3) copies for each location. That way, if there is a corrupted disk, the corrupt bits can be determined by "majority vote". I don't know of a program that does this, but it wouldn't be hard to write.

I would probably also refresh each site every 5-7 years to avoid relying on aged media. If I were in a position where I was concerned enough to back up my data off-site in three locations, I would take the additional precaution even if the disk vendor says it is not necessary.

Alex Hirzel
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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.

kirill_igum
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Best archive medium so far is DVD-RAM, but it's hardly available today. But you should still be able to grab one.

Don't expect normal burnable to last for more than 4 years, if you rely on them as your major backup no longer than 1 year. Keep them dark, dry and non-condensing cool. The problem is the organic dye used in those. DVD-RAM uses anorganic dye, which lasts about 10x long.

HDDs should be the best in price/capacity ratio and from my experience their lasting way longer than organic DVD-Rs.

Best would be tape, dvd-ram or stone plates.

bot47
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The best way to ensure long term archival is to use Error Correction Codes (ECC) codes such as Reed-Solomon, but they are complicated and long to calculate. This is way more efficient (in terms of resiliency against data corruption) than using a RAID 1 (duplication) scheme.

For DVDs and other optical mediums such as Blu-Ray, there is the great DVDisaster library with the RS03 scheme. It however runs only on Linux (old versions used to run under Windows, but they lack the RS03 scheme so I advise to use the latest release only).

About the reliability of various optical mediums and brands, scientific studies found that Blu-Rays are overall better than DVDs, you can read more info about it in my other answer here.

Community
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gaborous
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