Prevent data loss through degradation, by making redundant copies to disc

Question

I am about to store my PGP key to a 700MB disc. The key is (compressed) ~ 7KB in size. That is a whole lot space not used. A whole lot space that, if filled, could enable my drive to get at least one intact record of the file that is still readable, in case the disc is so degraded that without redundancy it would count as complete loss.

What would be the best way to do that?

Answer 1

There are a few things you can do.

One is to use an archival grade media such as Verbatim UltraLife, which is what I use for important local backups. Test results I have seen show they may resist degradation under optimal conditions substantially longer than an econ disc. The improvement seems to be mostly in the oxidative resistance of the reflective layer, the dye layer is generally the same as other high quality non-archival discs.

The second, as was suggested, is to make many copies of the same file on the disk. If a specific section of the disk is damaged, the data is still undamaged elsewhere. However many copies you can retrieve from a degraded disk can be compared, the average hamming weight per bit will most likely be the true value.

The third is to burn the disk at a slower speed, I have noticed over the years that 16X is about the max speed you can burn a CD before the reliability of the data in the long term becomes questionable. Consider burning at the slowest speed the drive and media will allow, but at least 4X. Higher burn speeds have more vibration, which leads to more jitter when reading.

And finally, keep the disk vertical in a hard case, somewhere out of the light, and at a cool constant temperature. Heat, moisture, thermal cycling, and light exposure will degrade the media.