Does Sync send different pieces or duplicates?

[Knowbody]

If a sync folder is shared among a group of 5 devices using the same internet connection as well as another group of 10 devices on another LAN across the internet, and a new file is added on one of the five computers, is Sync on each LAN computer going to send the same data 10 times into the other LAN (generating 50x internet traffic)? Or can it figure out that it only needs to send different pieces into the other LAN and let them sync among themselves?

 

[GreatMarko]

Sync is designed so as to bring your devices into sync as quickly as possible. It is essentially a "mesh" type network - i.e. all peers can send/receive data from all other peers.

Sync will determine the connection speed with other connected peers and use this to determine how much data to send/receive from each peer. For example, if you have 5 peers in your mesh all in sync, all with exactly the same upload/download bandwidth, and you add a 6th peer, the 6th peer will likely receive 20% of its data from each of the 5 peers - this won't be "duplicate" data, this would be different "pieces" of data, the sum of which would make up the complete file/folder.

Of course, in reality, not all 5 peers may have identical upload/download bandwidth capacity, or settings, and so some peers may be "faster" than others in your "mesh", and in these instances, Sync may prioritize more data from faster peers than from slower peers.

For more on the general background principles behind "Mesh networking", please see: https://en.wikipedia.org/wiki/Mesh_networking