Dropbox LAN Sync similar to syncthing (not that it's a big surprise)

Dropbox published an overview of how part of their sync works (Inside LAN Sync, HN comments), specifically how it can take advantage of LAN segments and avoid going outside the network for large chunks.

None of it is terribly surprising but can be nice to see validation and see how others are solving similar problems.

They get an easier time using a central point as a synchronized one-source-of-truth about file metadata and versions, instead of syncthing’s consensus algorithm.


Yes, the disadvantage of Dropbox LAN sync is that it won’t actually do it over the LAN until the file has been uploaded to the central server first. This is still annoying when you have big files to sync with other computers and you have a relatively slow internet connection (like at my current workplace for instance). You still have to wait for that first remote upload.