Are Verbatim's M-Disc Blu-Rays still really M-Disc? There was something about how they changed the recipe a few years ago, and the counter-argument was that Blu-Ray discs are non-organic anyway, which was the main feature of M-Disc DVD.
https://en.wikipedia.org/wiki/Golden_plates
https://en.wikipedia.org/wiki/M-DISC#History
Basically your media only needs to outlive your drives, retrieval mechanisms, software interfaces, and drivers. Or more properly, your backups need to outlive your live system and the need to restore any data from them. Certainly, data may be more precious than a live system, but you also need to concern yourself with format transfers, in terms of software file formats, filesystem formats, and media design/format.
This is not a difficult achievement. The people marketing long-term archival storage media are capitalizing on ignorance of people who have worked with books and photographs, which are "readable" by human senses. Books and photographs are media which can be preserved and fundamentally produced on archival media from the get-go.
Backup media, since it is necessary to have machines read and interpret them, are an entirely different beast, subject to an entire chain of things to preserve. As I've commented before regarding BD-RE XL, my media and the Blu-Ray drive itself outlasted the system it was backing up, and therefore did their job, without any investment or wasting money on M-DISC "Engraved in Stone Tablets" for the gentiles.
> While the immediate burn quality seems relatively satisfactory, I was still not satisfied as to whether these discs were truly worth their premium over commodity blank media. Looking at the discs, it seemed that the recording layers were likely made of similar materials based on the visual aspect, unlike the obvious difference with DVDs. Also, it seemed that regular recorders were intended to be able to record to the BD-R’s (according to the Verbatim text).
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> Digging further around the M-disc site, it is noted that their section on longevity testing actually features no data about the BD-R discs at all. Indeed, if there were tests, the reports were not actually featured on the site at all. Further poking around in M-Disc Technology pages shows only references to their DVD products. In fact, it seems their patented “etched in stone” material may only apply to their DVD products.
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> From my research into the data, it seems likely that the M-Disc BD-R is not substantially different from other quality BD-R discs on the market as they all use inorganic recording compounds (with the exception of BD-R LTH of course). From a visual inspection, the disc appears the same bright chocolate-brown, unlike the obvious distinction with regular dye based DVDs and the M-Disc DVD which was a silver-grey. But my main concern lies in the demonstrated lifetimes of quality BD-Rs which are similar to the M-Disc DVD (to which the M-Disc BD-R is claimed to have also achieved). In essence, it appears that the MKM/Verbatim BD-R DL has already reached the same level of endurance as the M-Disc DVD had claimed without being “special” at all. It is thus, hard to justify paying more for an M-Disc BD-R, and I cannot really recommend it.
The "not really M-Disc" stuff comes from a post somebody made on the "Data Hoarder" Reddit board a few years ago. The discs were changed to enable higher burning speeds which resulted in a slight difference in appearance, but he/she didn't seem to have realized that Blu-Ray M-Discs were never substantially different from BD-Rs and instead assumed that the tweaked discs were more of a scam than the originals.