bandwidth issue

[Gero Pflanz]

Hello, 

I have a question concerning the performance of rsync beteen two sites, one in India one in Germany. 

File exchange between 2 Linux-machines is done using rsync-3.0.5 (typical file size 1.5 GB).

Destination machine is: Linux machine1 2.6.9-55.0.9.ELsmp #1 SMP Tue Sep 25 02:16:15 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux

Source machine is: Linux machine2 2.6.18-53.el5 #1 SMP Wed Oct 10 16:34:02 EDT 2007 i686 i686 i386 GNU/Linux

ping between the two hosts yields in average 190ms. 

The bandwidth specified by the ISP is 6 Mbps. However, from rsync-logs I only

get 340 KB/s which is about 2.7 Mbps (typical file size is 1.5 GB).

Running 2 rsync processes in parallel I get 340 KB/s for EACH process, which

is 5.4 Mbps in total. Starting a third parallel process bandwidth is going

down, but the sum is still about 5.4 Mbps. 

I think the problem is related to the buffer size. Is it ok to change

buffersize with this command line option:

--sockopts=SO_SNDBUF=130000,SO_RCVBUF=130000

Is it sufficient to change only those 2 parameters ? 

Will this also change the buffersize af the other host (via rsync

communication)? In the logs I do not get any information that 

the sockopts parameter is changing something (although I am using 

"vvvv"). 

Any help or hint greatly appreciated. 

Thanks,

gp

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