Blu-rays are underrated for archival. 25GB or 50GB broadly available, almost impervious to scratches, even more resistant to degradation. Alas, the DRM for the movie side left a foul taste everywhere…
You can get them for what $12.50 a piece if you’re lucky and I’ve heard it’s only worse in Europe.
That’s 12 times the cost of hard drives. Buy just 6 or 7 and store them offsite and you have something that is more robust.
Once you hit the 50TB level it becomes economical to look into late gen LTO (tape), perfectly good LTO-7 drives can be had for cheap.
That’s 12 times the cost of hard drives
Where are you seeing $1 100GB hard drives, or $10 1TB ones?
https://www.amazon.com/Verbatim-98914-M-Disc-100GB-Surface/d...
$260 / 25 = $10.40/disc. $10.40 / 100 = $0.104/GB.
A decent 2TB HDD can be had for as low as like $60. $60/2000 = $0.03/GB. 10.4 / 3 = 3.46, so pretty far from 12x the cost. So realistically you could get three and a half-ish hard drives per gig compared to 100GB Blu-Rays.
I do agree, 100GB Blu-Rays do seem to be overpriced in some ways. I often end up using 25GB or 50GB discs as they're a lot cheaper and I often find I don't have another 100GB of data needing to backup. I mostly just wanted to point out its an option.
I wouldn't really compare them to hard drives in the end though. With optical media, its a disc that if stored even halfway decently will hold your data for longer than your great grandchildren's lives without needing to touch it or think about it again. A magnetic HDD has moving parts that will eventually wear out, magnetic surfaces that will lose their charge, need to be validated and re-checked and eventually copied over before failure. They're very physically resistant and very light weight. Dropping my CD case on the ground isn't likely to harm any of the data stored within, dropping a hard drive is likely to cause irrecoverable damage. Its way easier to mail to a distant family member to hold on to for long term distant storage. I can't easily mess up while copying the data and corrupt or delete it. The data is physically, permanently etched into the media. So no, I wouldn't say having 6 or 7 hard drives is more robust to having two burned Blu-Rays stored in two physically different locations in terms of trying to store the data for 50+ years.
There's a lot of things to like about using optical media for archival storage.
And yeah, if you're truly dealing with many dozens of TBs of storage you're needing to archive tape starts to make some sense, but I'd be more worried about procuring a tape drive able to read my tapes in 25+ years compared to finding some random Blu-Ray drive on eBay. Blu-Ray drives have been pretty mass market for a long time and will probably still be widely made for the next several years, meanwhile LTO drives are only really sold to enterprises in much smaller numbers. Also, lots of issues with backwards compatibility with LTO, so your options for getting the right drive is trickier. I'd imagine most home users are nowhere near there, and even a 25-50GB Blu-Ray a year/quarter would cover most of their data they actually care about.
I do think in these discussions Blu-ray resilience tends to be overstated:
https://www.reddit.com/r/DataHoarder/s/LhUnX4i3L6
https://www.degruyter.com/document/doi/10.1515/res-2017-0016...
> The data is physically, permanently etched into the media
This is hyperbole. Conventional Blu-Rays recordables and even M-Discs do not work this way, they work via phase change in an inorganic compound (or cheaper versions use organic dyes). Etched into the media makes it sound like a pressed product, which it is not, but that is another thing that needs to be considered: the substrate is not impervious to breakdown. These are also subject to QC problems.
https://www.reddit.com/r/DataHoarder/s/Na6F6lUFiL
There are very few suppliers of actually worthwhile Blu-ray media, and it is difficult to sort out what is real vs marketing mumbo jumbo.
Verbatim (CMC) changed their M-Discs in 2019 with a “it’s just as good, trust us”.
In any case if you need reliable optical backups you should be testing the burn quality. Many don’t do this, but then how do you know the disc has sufficient signal margin? This is specialist knowledge, which is why let’s be honest, most home users are going to best be served outsourcing this to a 3rd party. Perhaps make some Blu-ray’s as a supplement, but it is too easy to overstate the reliability of any one backup method, or losing sight of the big picture for one simple solution. Joe average home user should be considering a 3rd party service and even nerds can use tarsnap or something. Backup and preservation are systems, not a method. People underestimate the difficulty, effort and expertise, “home” users suck at it (as they should), most people need to outsource it. It doesn’t matter that the Blu-ray has 1000 years theoretical longevity if you burned garbage, and just getting people to the 10 year mark is tough. The only reason shorter time horizons are reliable is because of the massive uptake of cloud storage.
Blu-ray’s have their place I agree but it’s limited as a primary backup.
I've got some original and new Verbatim M-DISCs that I burned full with a few hashes. Every now and then I leave them in the patio for a few weeks but they often get used as coasters in my office. When it gets time to test I rinse them in the sink with soap and water and dry them with the kitchen towel. I test them every few quarters. So far they've lasted a decade and haven't lost a bit. One of them has some slow spots but so far they're all perfectly fine. Good luck storing a hard drive through thunderstorms and in 100F days in the sun for a decade and reading the data off them. I'm not too worried about their durability. And since it's $10 or less for a replica I can make a few and still not spend a ton.
And sure, that 20TB drive is $280. For redundancy I'll need to buy at least two. But I've only got maybe a terabyte or two I actually care about, so per terabyte it's a terrible price especially after buying 2-3.
And then when syncing new stuff I'd need to move the drives around as I'm talking offline archives. Kind of a pain to go copy all the data at a relative's place hundreds of miles away, I'd need them to plug it in. Otherwise they can just stash the discs in a box for me when I mail them every quarter or so.
4.7 GB was worth the cost and effort in 2004. 25GB in 2008? Not really.
Really? I heard that about a decade ago, the analysis barely made sense then but it seems even less sensible now. At Amazon scale tape is 0.5 cent/GB or less, hard drives are more expensive but easier to work with. Data storage on Blu-ray is tiny, still needs robotics.
But maintenance is much lower for optical. You can't just put those hard drives in a warehouse and forget about them. And BDXL is 100GB per disk. I don't know if the cost benefit makes sense here but it does seem somewhat possible.