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I wonder if this is actually cost effective. In my data hoarding days (as a consumer, not FB scale), I found burning media an archive tool to be much more cost

I wonder if this is actually cost effective. In my data hoarding days (as a consumer, not FB scale), I found burning media an archive tool to be much more costly (and less reliable and more physical space) than simply using multiple hard drives. Now, it could very well be that FB is able to buy burnable media at a much cheaper rate than consumers (i.e. perhaps there is more margin in media that massively bulk purchasing can reduce and the type of HDs that FB would buy would be more expensive than consumer drives, it could also be that actively used burnable media would be more reliable than actively used hard drives. while it's cold storage, its not frozen storage that is rarely used, with that said, the jukeboxes are probably expensive and suffer more reliablity issues than the hard drives), but on the consumer level, it just didn't seem to be a doable thing. Ex: 8TB HD could cost $120. That's ~ 400 25GB single layer blurays. Now, 400 disks of optical media no matter how efficient one can store them will take up a lot more room than a single 8TB HD. For the 400 bluray blanks to be cheaper than the HD, they would have to be less than 30cents a disk. Glancing at amazon today, the cheapest I see for 25GB BDR blanks (and dual/triple/quad layer blanks are more expensive per GB, i.e. a 50GB blank would be $1.6 a disc) is about 40cents a disk. At that price level, you are better off just buying/copying to multiple disks for even better disaster recovery and it wont really cost you more than to store everything once on optical media. anyways, if anyone could point out flaws in my assumptions (or why at FB scale the answers are different) I'd be interested.

ridgered4 3y ago
I'm also curious on how this could work and actually be more cost effective. I just can't see the robot being a reliable method and the cost savings being there. It almost sounds like some one's pet project. The only really interesting property of bluray is that they supposedly can last a very long time unlike other media, but I'd think you'd still want some redundancy at which point hard disks seem like the way to go.
Wilya 3y ago
At scale, you would need to factor in the durability of the media. [0] suggests that some types of bluray disks can last 20 to 50 years. Hard drives typically struggle to last 10 years. So if you need to replace hard drives 5x more than bluray disks, maybe it changes the economics. That's a random study I found on Google, of course, I'm sure Meta has more accurate data on that. Besides, you need to build the same kind of redundancy in both cases, so that shouldn't influence the choice. [0] https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/canadian-conservation-institute-notes/longevity-recordable-cds-dvds.html https://www.canada.ca/en/conservation-institute/services/con...
- antisthenes 3y ago
  > At scale, you would need to factor in the durability of the media. [0] suggests that some types of bluray disks can last 20 to 50 years. Hard drives typically struggle to last 10 years. So if you need to replace hard drives 5x more than bluray disks, maybe it changes the economics. Also consider the economics of actually retrieving and indexing the data. If you have to spend 2 hours looking for a blu-ray/DVD with the data you need, then maybe it changes the economics back to HDDs, which can look up a file within 20 TB of data almost instantaneously using an NTFS Journal.

ridgered4 3y ago

I'm also curious on how this could work and actually be more cost effective. I just can't see the robot being a reliable method and the cost savings being there. It almost sounds like some one's pet project. The only really interesting property of bluray is that they supposedly can last a very long time unlike other media, but I'd think you'd still want some redundancy at which point hard disks seem like the way to go.

Wilya 3y ago

At scale, you would need to factor in the durability of the media. [0] suggests that some types of bluray disks can last 20 to 50 years. Hard drives typically struggle to last 10 years. So if you need to replace hard drives 5x more than bluray disks, maybe it changes the economics. That's a random study I found on Google, of course, I'm sure Meta has more accurate data on that. Besides, you need to build the same kind of redundancy in both cases, so that shouldn't influence the choice. [0] https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/canadian-conservation-institute-notes/longevity-recordable-cds-dvds.html https://www.canada.ca/en/conservation-institute/services/con...

antisthenes 3y ago
> At scale, you would need to factor in the durability of the media. [0] suggests that some types of bluray disks can last 20 to 50 years. Hard drives typically struggle to last 10 years. So if you need to replace hard drives 5x more than bluray disks, maybe it changes the economics. Also consider the economics of actually retrieving and indexing the data. If you have to spend 2 hours looking for a blu-ray/DVD with the data you need, then maybe it changes the economics back to HDDs, which can look up a file within 20 TB of data almost instantaneously using an NTFS Journal.