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Superior Longevity of Blu-Ray / M-Disc vs. Tape Backups?


I’m wondering which option would be the most desirable, from a longevity (data integrity) point of view - optical (Blu-Ray) or magnetic tape?

Is tape still superior?

AFAIK Mdisks will outlive tape, however, they don’t hold as much as tape. They are also a “one and done”.


If you don’t mind, let me ask for your source.

Back in the early 2000s, i’ve been taught that mag tapes are superior, but that was - in terms of tech evolution - aeons ago. :smirk:

MDisk, AKA Millennial Disc, … last for 1000 years.


Blu Ray is roughly 20 to 50 years depending on the physical makeup of the disc per the Canadian Conservation Institute.

Tape is roughly 30 years per HPE.

This is assuming both are stored in a perfect environment.


Oh wow, those use oxygen-inert recording layers ← yeah, that’s what i was worried about.

Also, actually / physically “burning” a disc (as in actual lands & pits) seems much more reliable than merely changing the “color of an oxidating organic dye”.

Even 10% of their advertised longevity is still 100 earth years …LOL, that’s more than enough for my particular thread model :joy: :+1:

If anyone likes to contribute longevity / integrity rating for tape media …you’re welcome

Problem with tape for long term storage is the generations of compatibility - so current lto 8 drives can only go back to lto 6 for reading - so you aren’t just relying on the tape lasting but also your drive, or the availability of drives that can read that generation.

They’re great for enterprise, and the several year timescale, but talk about decades and I think something like m-disc that can be read on common hardware makes sense.

Otherwise it’s a question of being a good archivist and transferring your old data onto new media as it becomes available.


Solid state will trounce spinning rust any day for longevity.

Doesn’t solid state drives need to be connected to power every few years or so?
Like just a little power, but can’t be shelved for decades and then read all data

I am yet to find a study that supports those claims, I have only ever found articles of theoretical speculation.

Right, but neither have I seen any studies that disproves these claims, or any studies at all on it.

So if we then cannot rely on a rigorous peer-reviewed research study, probably the next best option is to rely on the manufacturer and similarly knowledgeable people.

So basically, we don’t know for certain one way or another what properties of nand flash (SSDs) are long term (over decades as mentioned), but the people in the know are not confident that the data will last that long on flash.

So, then if you are looking for a reliable long term archival solution, don’t look to flash, look to other solutions which have been developed and studied to be suitable for long term storage.


I looked into this a while back, and I found this.
It’s not from a big review site.
But some guy tested the durability, and it’s definitely tougher. I think it’s a good indicator that it’ll last longer. But in the end, only time will tell :slight_smile:

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How is optical archival better than HDD using Raid (with single or dual parity)? It seems dual parity HDDs could rival these M-Discs - you’d just have to replace dying and/or dead drives, and not always have them running…

Well, M-discs would be for cold storage of data which aren’t going to be changed, and which you don’t need frequent access to.

A raid array is more for actively used and changing data, which you need frequent access to.

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I am on my long term data storage journey. I have some Low to High bluray discs that are two years old now. Just read them last night. No data degradation, yet. They are 4x and 6x speed single layer. I wrote them at 2x speed. I put 20 ish gigs in the disc and filled the rest with ecc data using dvdisaster. And before I filled the discs, I used dvdisaster to make an ecc file at 33% of the data. Every 3 discs I write a separate ecc disc with the ecc data from 3 discs.

I have started some duplicate copies of the discs with some cheaper High to Low blurays. We will see how long they last. Oldest is only 1 year, but reads fine as of last night.

you know you can write out the contents of a raid disc to a tape, and back?

So can have a whole raid backed up, with parity, as tape?

Recovery is a bit arduous though

Ya, it is a good point. And I imagine the same could be done with optical storage. I wonder if there is any software that could help a ZFS raid array -> optical disc writing session.

For raidz2 array, losing a little data is no problem at all. Losing too much and you could lose everything. On the other hand, with optical if an optical disc is damaged, then it could be very hard to read from it and you could lose the whole disc (without specialty equipment).

Best guide I’ve seen - seems like you put thought into it. So which writer & media do you think is best (and what did you get)? I’m guessing a consumer-grade writer & some high quality media (blu-ray, m-disc)?