Why use Atlas instead of using Kademlia DHT?

[larry]

One of the problems with Kademlia DHT was ensuring that a given zone file exists as nodes enter and leave the DHT. We used to have special nodes that were “DHT mirrors” - tasked with keeping a long term copy of all items seen in the DHT to try to achieve that.

Another was the problem of performance and slow look up time.

There might have been other issues as well…if we’re nice, perhaps @jude will elaborate on those.

As to how Atlas functions:

@jude

Atlas is a lot like BitTorrent. Each Blockstack node treats the sequence of zonefile hashes in the blockchain like a .torrent file. The nodes try to connect to a bunch of peers and use BitTorrent’s “rarest first” chunk-fetching strategy to prioritize replicating less-durable zonefiles. Instead of using a tracker, they use a stochastic peer-sampling algorithm that is known to be good at getting a random sample of peers in a dynamic network graph. We went with this approach because random overlay networks are more resilient to node failure in practice than structured overlay networks like DHTs.