Optical media lifetime - one data point

Way back (more than 10 years ago) when I was doing DVD-based backups, I knew that normal DVDs/Blu-Rays are no long-term archival solutions, and that if I was real about doing optical media backups, I need to switch to M-Disc. I actually bought a (small stack) of M-Disc Blu-Rays, but never used them.

I then switched to other backups solutions, and forgot about the whole topic. Until, this week, while sorting stuff, I happened upon a set of DVD backups from a range of years, and was very curious whether they are still readable after many years.

And, to my surprise, there were no surprises! Went backward in time, and:

• 2014, TDK DVD+R, fully readable
• 2012, JVC DVD+R and TDK DVD+R, fully readable
• 2010, Verbatim DVD+R, fully readable
• 2009/2008/2007, Verbatim DVD+R, 4 DVDs, fully readable

I also found stack of dual-layer DVD+R from 2012-2014, some for sure Verbatim, and some unmarked (they were intended to be printed on), but likely Verbatim as well. All worked just fine. Just that, even at ~8GiB per disk, backing up raw photo files took way too many disks, even in 2014 😅.

At this point I was happy that all 12+ DVDs I found, ranging from 10 to 14 years, are all good. Then I found a batch of 3 CDs! Here the results were mixed:

• 2003: two TDK “CD-R80”, “Mettalic”, 700MB: fully readable, after 21 years!
• unknown year, likely around 1999-2003, but no later, “Creation” CD-R, 700MB: read errors to the extent I can’t even read the disk signature (isoinfo -d).

I think the takeaway is that for all explicitly selected media - TDK, JVC and Verbatim - they hold for 10-20 years. Valid reads from summer 2003 is mind boggling for me, for (IIRC) organic media - not sure about the “TDK metallic” substrate. And when you just pick whatever (“Creation”), well, the results are mixed.

Note that in all this, it was about CDs and DVDs. I have no idea how Blu-Rays behave, since I don’t think I ever wrote a Blu-Ray. In any case, surprising to me, and makes me rethink a bit my backup options. Sizes from 25 to 100GB Blu-Rays are reasonable for most critical data. And they’re WORM, as opposed to most LTO media, which is re-writable (and to some small extent, prone to accidental wiping).

Now, I should check those M-Disks to see if they can still be written to, after 10 years 😀