I've read the many articles, some of which contradict each other about whether dye based CD-R/DVD-R are more archival or less archival compared with CD-RW/DVD-RW discs with metallic film. Since the experts can't seem to agree, I'm interested in the experiences of other photographers, regarding long term experiences with CDs/DVDs. (And, yes, I'm considering the M-Disc, although I'm not sure my existing drives are compatible.) For the past week I've been copying decade-old and older photo CDs and DVDs to a new 3 TB hard drive. So far I've encountered only a few bad discs. But there's no apparent pattern. Some discs with unrecoverable photos were CD-R, some were DVD-R. There doesn't seem to be any pattern of failure attributable to brand, or type within a brand (e.g., Maxell CD-R vs Maxell CD-R Pro). And there aren't enough failures to spot any patterns. I've used mostly Maxell and Fuji CDs, and Sony DVDs including DVD-RW and DVD+RW. I also have a few CD-RW from Office Depot that turned out to be rebadged Sony or other good brands (according to Nero's disc inspection utility). The most significant failures were CDs burned by pro labs and minilabs from my film scans 10 or more years ago. Those appear to have fared significantly worse than my own burns. The only pattern I've noticed was an immediate failure with some CD-R and DVD-R discs I burned years ago with an outboard USB 2 Lite On drive, but I was able to minimize those burn errors by reducing the write speeds. At full write speed I was getting about 50% failure, especially with DVDs. But reducing the write speed improved successful burns to around 90%. I'd guesstimate 97% of the discs I burned successfully up to 10 years ago with the Lite On are still good. I haven't used enough dual layer DVDs, DVD-RAM or DVD-ROM discs to say anything. Maybe half a dozen and all appear to be okay. As an experiment, about 10 years ago I began burning important long term documentary projects to both CD-R and CD-RW; and DVD-R, and DVD-RW or DVD+RW discs. So far all of the rewritable discs, and most of the write-only discs, are still good. The only interesting observation is that the rewritable discs have fared as well as the write-only discs. This seems to contradict the conventional wisdom of the previous decade that rewritable discs wouldn't last as long. One reason I'm reconsidering my whole approach is because my options for off-site storage are very limited. I have a couple of friends and family members who may be willing to store a carton of CDs/DVDs for me. But there are no guarantees about storage conditions. One family home where I left a carton of discs was left un-air conditioned for several years, and a plumbing leak flooded the entire house, along with those discs and some of my negatives and slides. Any cartons I leave with other folks may very well migrate to garages, attics or basements. All I can do is pack the discs in sealed plastic bins and hope for the best. (Military surplus ammo cans also hold up very well and are flood resistant, but I'd need to repaint those into something friendly to make them less ominous appearing.) I don't really have any options for off-site storage of backup hard drives, so those stay with me. Any off-site storage will be limited to CDs/DVDs as a last-ditch method. Beyond that, my best bet is probably cloud storage with Amazon, which has affordable rates provided you don't need immediate or frequent access to the files. Anyway, mostly I'm curious about your long term experiences with various types of CDs and DVDs.