I would prefer a torrent backed by Amazon S3.
A torrent can be generated for any file that is publicly accessible on S3 by appending
?torrent to its URL. Stack Exchange Inc. could then redistribute the torrent file without telling people the original S3 URL so that they would actually use the torrent and not just grab the file with HTTP. (It's possible to figure out the download URL from data in the torrent file, but hopefully the majority of users wouldn't.)
The torrent will be seeded as long as SEI makes it available on S3. However if SEI or Amazon stops supporting this, the torrent can still continue without them; because it's not marked as
private users can continue to download from other peers without support from Amazon's tracker.
The major drawback of this approach is that it can only be used to generate a torrent for a single file, not a collection of files. The dump would need to be consolidated into a single file or split across multiple torrents. One possibility going forward would be for torrent of new dumps to only contain data that has been added or changed since the last dump. This would keep their individual sizes relatively small and allow users to update their local copies without redownloading the data they already have.
I really like this idea in theory, but I don't really know how well the feature actually works. I've tried it out a few times (here's an S3
?torrent download for you to try). My unscientific impression has been that Amazon's seed is activated after the
?torrent file is first downloaded and shuts down after the torrent is inactive for some amount of time. It is never restarted, even if the
?torrent file is downloaded from Amazon again. Later downloaders seem to be out of luck.
Maybe there's some way to avoid this, but the only official docs I could find don't mention it and haven't been updated in seven years... we probably shouldn't rely on this feature.
As sth remarked, why can't Stack Exchange Inc. just seed a torrent? It would be supported by you but wouldn't depend on you. This doesn't seem like it would be too demanding on your servers or network.
I also don't understand why you would need a contact at Amazon for S3 to be viable. They have bulk import options available already, and I don't think this would be enough traffic that it would justify custom pricing or anything (unless due to some sort of promotional thing). Is there another reason?