Rsync download traffic

[jw schultz]

On Thu, Oct 16, 2003 at 09:38:32PM -0500, Max Kipness wrote:
> > > I started monitoring lan traffic with RRDTool on a linux
> > > box the other day that runs rsync, and I've found what I would 
> > > consider a strange traffic pattern. This linux box rsync 
> > about 2Gb of 
> > > data to a local samba share that is connected to a Windows 2003 
> > > server. Based on the literal data stat, roughly 20% is 
> > changed nightly 
> > > and uploaded. However, the strange thing is that the traffic 
> > > monitoring shows that there is 3mb/s saturation both ways, 
> > upload and
> > > download (somehow the server only had a 10mb ethernet
> > > adapter).
> > >  
> > > This behavior could not possibly be correct, could it? Or
> > > is this normal. If needed I can post some stats and
> > > command line options.
> > 
> > Why couldn't it?  Fast disks and CPU will easily overrun a
> > 10Mb connection for network file service.  Don't forget
> > 3Mb/s is only 300KB/s compared to 5-30MB/s for disks.
> 
> Sorry, I meant to emphasize the point that saturation occurred both
> ways, inbound and outbound. I can understand the saturation on the
> upload as it is transfering changed files up to the destination, but
> what is it downloading that is so large?

I assume by upload you mean write and download, read.

stat(), readdir, and if --no-whole-file reading so it can do
checksums followed by reading in order to merge matched
blocks with new.

> > Your description leaves a couple of important things out: 
> > version of rsync and how rsync views the transfer with regard 
> > to networking.
> 
> Rsync version 2.5.6. Both servers are on the same local segment.

As rsync views the transfer, not the physical layout.
A local smbfs mount does not look to rsync like a network
tranfer.

> 
> > Make sure that rsync is doing a --whole-file transfer. 
> > Otherwise it will really thrash the destination.
> 
> I am not doing --whole-file transfer, but will try that for the session
> tonight.
> 

-- 
________________________________________________________________
	J.W. Schultz            Pegasystems Technologies
	email address:		jw at pegasys.ws

		Remember Cernan and Schmitt