Needing a little more explanation about Bittorrent Sync

[tridephysique]

After reading description and explanation about bittorrent, I understand most of it except one:

How can Bittorrent Sync be fast? In my imagination/thought, if I set up Bittorrent Sync to sync folders on my PC (which may be hundreds of GB) to my laptop, there will be only 2 peers - my PC and my laptop. My internet connection's upload speed is only 512 Kbps (~64 KB/s). The no way to complete synchonizing.

Does Bittorrent Sync first make other PCs (which do not belong to me) be peers to speed up the process.

If so there are more peers than just my PC and laptop and encrypting ensures that the orther PCs which involve do not see my files?

[Varnagas]

I hope to help you out here.

Sync can be fast compared to cloud solutions because it is direct and immediate. Unlike cloud, it sync to your other machines asap, while cloud wants to get copy first and only then distributes it to other peers. Because of that syncing in the same local network with cloud is waste of time. BT sync allows you to have all the traffic your network or machines can deal with.

Even when peers are not in the local network, cloud services (free accounts for sure) limits traffic for you. So if you have quite capable connection, direct traffic is also way faster (and with no delay by cloud) than with any means in the middle. Yet again BT sync aims to give you all the traffic speed your networks and machines allow.

Sync won't connect other pcs that don't have sync key to speed up your sync. But it uses relay server (if allowed by settings) to enable (and speed up in this sense) sync, while it may not be possible without it. Relay server is administrated by BTsync team and they tell us they can not see what files are transmitted and they do not store any transmitted data.

Does that explain it?

[tridephysique]

Thank you, Varnagas

Now I understand. So for any situation BTsync is always usefull. For several hundreds MB, sync over internet is ok. For hundreds of GB and low internet connection, it is better to sync over local network.

In my situation, my large folder better needs to sync over local network for the first time. After there will be a few changes which I will sync it over internet for convinience.