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This recent HN discussion has a lot of information about the reliability of optical discs: https://news.ycombinator.com/item?id=30888906 https://news.ycombinato

This recent HN discussion has a lot of information about the reliability of optical discs: https://news.ycombinator.com/item?id=30888906 https://news.ycombinator.com/item?id=30888906 My main comment has some hard numbers based on my own experience: https://news.ycombinator.com/item?id=30889474 https://news.ycombinator.com/item?id=30889474 In short: 77% of the discs I ripped after ~15-18 years had minor issues as demonstrated through read errors (when ripping with ddrescue) and checksums (in png, zip, and gz files; I did not manually checksum files back in the day). I was able to rip 99.88% on the worst disk, and I estimate that about 97% of the files are intact on that disk. CDs and optical discs more broadly seem to be reasonable, but I'm not really sure they'll be in good shape after 30 years. I'd consider them part of a backup strategy, not an entire backup strategy. I personally use a combination of external (magnetic) hard drives, flash drives, and optical discs for backups. Replacing the optical discs after 10 years or so seems prudent, as is redundancy and/or par2 files.

fredophile 4y ago
CDs and DVDs are cheap and burning them is fast and easy. Make several copies, calculate the checksum, and store them in different places. Every few years see how badly they've degraded and after hitting some pre chosen threshold you can return all of them. If their data really is less than 1 GB they could even store 4-5 copies per DVD for additional redundancy. Even on a single disk I'd imagine the errors are unlikely to be in the same region on all 4 copies.
- vikingerik 4y ago
  Optical media doesn't hold enough, though. I've got a terabyte of downloaded media. Even with Blu-rays that hold 50 GB, I'm not going to bother burning and storing and keeping 40 of them. I go with simple external hard drives. I get a new one every couple years and copy everything to it as my main backup. The likelihood of my in-machine drive and fairly young backup drive failing at the same time is pretty low. Even if that happens, the previous backup drive will have a good portion of it. And my important docs folder also goes to Carbonite online backup.
  - fredophile 4y ago
    That's your use case (and probably fairly common). The original question specified < 1 GB so my comment was based on that. If I had to save 1 TB I'd probably save 1 copy with a specialized storage provider, 1 hdd in a safety deposit box and 1 hdd at home. You could also use tapes if you don't trust the HDD hardware to last.
  - mixmastamyk 4y ago
    Blu-ray holds more than that.

fredophile 4y ago

CDs and DVDs are cheap and burning them is fast and easy. Make several copies, calculate the checksum, and store them in different places. Every few years see how badly they've degraded and after hitting some pre chosen threshold you can return all of them. If their data really is less than 1 GB they could even store 4-5 copies per DVD for additional redundancy. Even on a single disk I'd imagine the errors are unlikely to be in the same region on all 4 copies.

vikingerik 4y ago
Optical media doesn't hold enough, though. I've got a terabyte of downloaded media. Even with Blu-rays that hold 50 GB, I'm not going to bother burning and storing and keeping 40 of them. I go with simple external hard drives. I get a new one every couple years and copy everything to it as my main backup. The likelihood of my in-machine drive and fairly young backup drive failing at the same time is pretty low. Even if that happens, the previous backup drive will have a good portion of it. And my important docs folder also goes to Carbonite online backup.
- fredophile 4y ago
  That's your use case (and probably fairly common). The original question specified < 1 GB so my comment was based on that. If I had to save 1 TB I'd probably save 1 copy with a specialized storage provider, 1 hdd in a safety deposit box and 1 hdd at home. You could also use tapes if you don't trust the HDD hardware to last.
- mixmastamyk 4y ago
  Blu-ray holds more than that.