On 2021-10-23 Adam Thompson wrote:

...so here's a periodic reminder that the centuries your optical discs were supposed to last? Let's call that *highly optimistic at best*.

I know several people reading this who back up to optical media, but only one (maybe two) who plan for media longevity.

Funny, I recently did a little study of my own and was going to make an article about it or something. Still probably will.

I've been backing up to CD-R and DVD-R for about 15 years. So I took the oldest 500 discs a while back and started running checksums on the all to see if any had problems (and compare against original checksums I still have).

So far I have 1 CD that seems to be having issues. Out of hundreds. And since my backup system breaks things up into 10-20 chunks per disc, my loss of 1 file is only about 50MB. I am still trying to figure out if anything else might be going on (i.e. physical damage).

All in all they seem to hold up even better than I had expected.

On 2021-10-24 Hartmut W Sager wrote:

It was pointed out that, longevity aside, you need compatible reading hardware later to read the discs. For both reasons, I re-write (copy to elsewhere) everything every 2-3 years. I no longer use CD-R/DVD-R

Funny, that's exactly what I do. My program is currently set to rewrite every 5 years. I started at 2 years, but as I went on without issues I kept upping it to save media. I use a mix of cheapo and datalife plus. So far there doesn't seem to be much difference in reliability to be honest.

Optical media: the only backups that will survive an EMP! :-)