[Fixed] Suboptimal Performance, Btsync 1.3.94

[JimKnopf]

Hi,

I’m a member of a very small btsync network (4 clients) where the most of us use btsync ARM 1.3.94 on Synology NAS or Raspberry Pi platform.

 

We have to synchronize large data files and discovered a suboptimal behavior of btsync regarding performance which can be easily reproduced:

Imagine you have 3 clients A, B and C where A is able to see B but not C.
B can see both others clients.
This can be a situation where A is a system in the internet, B in a local network WITH access to the internet but C is a client in the same local network but WITHOUT access to the internet and only able to see B, so the test configuration is:

 

A <-> B <-> C

The upload rate A -> B is SMALLER (this is important!) than the upload rate B->C.

 

When client A starts to synchronize a very large data file with B but C is still offline then there will be with growing time more and more data on B which will be synchronized with C once it is started.

 

If C is now started and it empties the amount of data on B to be transferred to C by the high upload rate from B->C BEFORE A has finished its upload to B then any new data on B WILL NOT be transferred to C until the upload from A to B has ended or the btsync client on C was restarted.

 

In other words while the transfer of data from A to B there is no continuous data transfer between B and C once the client C thinks it is in synchronal state with B by no new data. C has to wait until the upload to B has finished before it gets new data … which is of course not very efficient.

 

The upper configuration is just to express a simple environment; the issue also happens if all clients are connected via internet connection but a receiving machine has higher upload to the others in the network than the link between the first sender and this receiving client.

[RomanZ]

@JimKnopf

 

Seems we've managed to simulate behavior in our lab. Thanks for reporting, we'll analyze this issue.

[JimKnopf]

Thx a lot for caring.

 

As a non-native English speaker I already feared that my description was too incomprehensible.

Our workaround for now is to cut all large files to very small pieces by using archive programs like 7-zip.

[JimKnopf]

1.3.109 fixed this. Thx a lot to improve the synchronization speed by this.