How to improve transfert rate with rsync

[Steve Bonds]

On Thu, 13 May 2004, guy cadoche guycadoche-at-mail.com |Rsync List|
wrote:

> 1) I am using rsync with gentoo and all emerge are very fast 400 kb/s
> ADSL connections. When I am using rsync with two computers with the same
> bandwith connection (ADSL 400 kb/s) transfert is very low (40 kb/s).
> options are "rsync -avzub". How can I improve the rate of transfert ?

ADSL is an asynchronous DSL line with different upload and download
speeds.  I suspect that you're hitting the upload speed cap when sending
files.  To verify this, grab a copy of netperf:

http://www.netperf.org/

This tests the raw throughput across TCP connections.  Nothing will ever
be able to transfer raw data faster than the rate it shows.  While you
may be able to download at 400K/s, uploads might be MUCH slower.

> I saw That it use sftp. Is there a configuration file for sftp that
> improve the transfert ?

Often the use of ssh (not sftp) with rsync slows it down since the system
CPU needs to encrypt the data and any network devices that would normally
compress the data will be thwarted.  On modern CPUs across slower networks
(i.e. 10Mbit or below) this shouldn't be a major bottleneck.

> 2) How can I see the transfert rate of the file (like with scp)

Check the rsync option "--progress", best used with "--verbose".

  -- Steve