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I'm considering moving from DVD-Rs to Blu-Ray Recordable disks to backup my data. I don't have any experience with BD-Rs as of yet, though, and I wonder if it's worth it or I should wait another year or two.

I clearly remember that when DVDs were still the new thing you could reasonably expect a 20% coaster rate, and after one, maybe two years a lot of successfully recorded disks became totally or partially unreadable. Same thing happened years before with CD-Rs.

Considering that as of January 2012 the price of a single BD-R hovers around $2.40, and considering that I need at least 200 of them to move my data, I'm now treading lightly.

I'd appreciate to hear from someone who made the switch and can speak from experience.

As an aside, the cost per gigabyte of BD-Rs seems to be only slightly higher than DVD-Rs': $0.096 for BD-Rs (25 / $2.40) and ~$0.070 for DVD-Rs (4.3 / $0.3). The higher density of BD-Rs, in my opinion, compensates for the slightly higher price. Still, reliability comes first.

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  • Update about hard disks: Answers so far have been of the "the heck with BD-R, use hard disks" kind or "permanent backup is a myth". So let me clarify my position on both. First off, I know, "permanent" is really not permanent. When I say that, I mean 5-10 years. Technology marches on. Now, hard disks: I approach them with paranoia, because they fail often and unpredictably. For instance: last year I bought two 1.5TB Seagates. Filled them with the most accessed data, kept one online, the other stashed away. The one kept online failed within three months.
    – Yudo
    Jan 15, 2012 at 19:34
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    If used properly, hard drives can be very reliable. The key to success is using them in a redundant array, where depending on the setup, one or two discs can fail without any data loss. One good way to achieve this is to create a RAIDZ or a RAIDZ2 array with ZFS. You can set up your workstation to periodically check the integrity of the stored data, so if a drive was failing you would have time to react and replace it, without losing data.
    – phil
    Jan 15, 2012 at 20:05
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    I've eaten three hard drives in the last two years, and my data is still safer in my opinion than if I were to write them every three to five years to DVD or BD. I have around 4TB of data, mirrored across at least two drives at a time. It's a manual RAID1, for lack of a better definition, not perfect by any means, but it's still more reliable than the BD scenario. I tried reading a CD-R I burnt in 2006 and it saw the files, but I couldn't read them.
    – user3463
    Jan 16, 2012 at 4:34
  • @RandolphWest: I've gone through at least 6, if we take into account the refurbished manure that Seagate kept sending as a replacement, which itself had to be replaced within two months. Eventually the combined shipping cost was approaching the cost of a new drive (seriously), so I stopped sending them back. That's why I feel kinda paranoid. However yes, all things considered the BD scenario seems to have more cons than pros. I think I'll ultimately stick to what I am doing right now (manual RAID1 is a great definition, actually!) and get some more drives as soon as prices drop.
    – Yudo
    Jan 16, 2012 at 8:22
  • If I can suggest anything, it is to avoid Seagate. That said, Western Digital Blue snf Green drives haven't been behaving at all well lately, leaving the Black ones which are pricier.
    – user3463
    Jan 17, 2012 at 1:11

6 Answers 6

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I seriously would recommend you get HDDs as a backup:

Reasons:

  • They are cheaper
  • You can keep your data always up to date
  • You can plug them in anywere
  • Faster Backup

If you check HDD prices today, they are probably quite high, this is still due to the flooding in Thailand, which made the prices for HDDs explode - doubled prices!

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  • All things considered, I agree, thanks. I would accept your answer (and upvote the others) but unfortunately I don't have enough reputation to do so.
    – Yudo
    Jan 25, 2012 at 0:35
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    Those are strange arguments for the choice of backup medium: (1) Unless you back up frequently, the difference in cost between HDD and BD backup is not that significant (in 2012 or now). (2) It's backup. For up-to-date data you use HDDs. (3) No you cant; unless it's an external HDD - but you can also use an external BD player. (4) Again, for backups that are not super-frequent - that's a minor consideration. Bottom line: The major consideration should be longevity.
    – einpoklum
    Jan 5, 2017 at 22:55
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There is no perfect way to keep data, all media will degrade over time. The best way is multiple backups, probably on different media, kept on different sites to guard against fire, flood, etc.

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    Already doing that. The data I have on DVDs I also keep, partially, on hard disks. Switching to BD-R would also give me the opportunity to countermand the degradation - which is certainly affecting my DVD-Rs as we speak - by moving the data to "fresh" media. Just like I did 10 years ago with my CD-Rs.
    – Yudo
    Jan 15, 2012 at 19:44
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200 BD-R discs * 2.40 = 480$

4 * Seagate Barracuda Green ST2000DL003 2TB 5900 RPM * 150.00 = 600$

If you set up a ZFS RAID-Z array, you would have 6TB of available space and one drive could fail completely, before you would be in trouble.

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  • you can't count the barracudas with a price of 150(assuming $) each, that's only a temporary high.
    – inf
    Jan 15, 2012 at 19:17
  • I know that very well, however if he needs them right now, that's what he will have to pay for them.
    – phil
    Jan 15, 2012 at 19:36
  • $580, actually, since I'd have to buy a BD-R recorder as well. Good suggestion, but we all know that drive will fail. On my personal reliability scale, HDD rate pretty low. I'd rather buy two 3 TB drives at $250 each (current price) and use the same technique I talked about in the comment above.
    – Yudo
    Jan 15, 2012 at 19:40
  • ZFS should work in machine with ECC RAM. And it is not a chip one PC
    – pugnator
    Mar 4, 2015 at 17:50
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    But the HDDs will die long before the BD-R's will - typically, under a decade vs supposedly many decades. Also, BD prices are ~50% lower now (same price but for BD-R DL 50 GB).
    – einpoklum
    Jan 5, 2017 at 23:11
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I was also wondering if BD writers are reliable now. I agree with Xavierjazz - back up to different types of media, and keep them in different locations. I suppose using the "cloud" would be convenient - it is in a different location, but you don't need to leave your home to access it. I definitely wouldn't use the cloud as my only means of backing up though.

Now back to the BD question. I know that in the CD/DVD world, Verbatim and Taiyo Yuden are the top brands of media, so perhaps that is still true when it comes to BD media. Also, after you have burned a CD or DVD, you can use a free program called Nero CD-DVD Speed to test the media and it will give you an idea of what the burn quality is. For example, it reads the media and tells you how many errors the drive encountered (yes, even with perfectly readable media, all drives will encounter thousands of errors - that is normal and part of the specification for optical media). For BD media, there's a new version of the program called Opti Drive Control, which is payware and which I haven't used.

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A study was conducted by the french National Archives in 2012 about the viability and resiliency for long term storage of various Blu-Ray discs brands and BR writers.

What they found is that not all Blu-Ray discs are equal, and the most resilient were of the HTL type. Also, the optical writer impacted quite a lot on the resiliency of the Blu-Ray (they tested writing with different optical writers on the same blu-ray brand).

Nowadays, Blu-Rays have become affordable (both the writer and the discs), so we could say that if you take care of using the correct writer and discs (HTL), you can have a cost effective reliable long term storage medium. Also you can add a layer of protection using DVDisaster error correction codes. But this will always be more complicated and time consuming than using a simple hard drive...

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    How can I know which BD's are of "LTH type" when I buy them?
    – einpoklum
    Jan 5, 2017 at 23:11
  • @einpoklum When it's HTL, generally there will be a mention about it written on the discs package, because they are more expensive to produce and are seen (with reason) as being better quality. If you don't see any mention, it's often LTH type. But the best is just to find the technical characteristics online, either on the brand's website or on collaborative databases.
    – gaborous
    Jan 7, 2017 at 0:22
  • Looking at NewEgg, I only see LTH mentioned specifically, so presumable the default is HTL. I haven't seen any Blu Ray media advertized as HTL. Are you sure you're not mixing them up?
    – einpoklum
    Jan 7, 2017 at 0:46
  • @einpoklum my comment is solely based on my own experience so your mileage may vary. I had a hard time finding HTL discs whereas LTH was easier (eg, there are a lot more Panasonic LTH available online than Panasonic HTL). However here is another approach that is possibly more reliable (but it requires you to first buy one disc to check its code, or find it somewhere online beforehand): superuser.com/questions/879216/…
    – gaborous
    Jan 7, 2017 at 1:02
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The prices of decent HTL BD-R discs have come down to just above $20 per 50. The technology is similar to the technology used in DVD+R M-Disc media, which makes it seem pretty reliable to me.

I have a few I burned a few years ago, and they are still readable. My caveat is I wouldn't use any capacity higher than 25GB, single layer, and if you have TB of data, this would take quite some time to burn, and quite a bit of space to store.

That said, I would still use BD-R media as one leg of a more complete backup solution. I have a second hard drive in my computer dedicated to backed-up data, plus my roommate's NAS, plus optical, plus cloud storage. The cloud storage is encrypted and archived to 7zip files (protected by a 30+ character password), so no prying eyes can see my data.

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