SCP speed question

[James McDonald]

Alma J Wetzker wrote:
> What speed should you get with scp on a 100 Mb/s backbone?  I backup my
> home directory with scp to my server and I am getting 3.8 MB/s.  That
> seems a bit slow to me.
>
>     -- Alma
>   
I have found that when you purchase a cheap 10/100 switch and do 
bandwidth test on it using something like ttcp (which writes raw data to 
a ttcp listener port running on hte remote computer) that it is rare to 
get 100M/bs. First step I do is test through put between the computers 
using a cross over cable and sometimes the linux drivers for cards don't 
perform very well either. Once I know that then I plug the computers 
into the switch and do another ttcp test in both directions to find max 
thruput.

So I would test the fabric first to find it's peak bandwidth capability 
and then look at what percentage of this total figure scp is running at. 
Then you can check how much the ssl encoding is sucking out of the process.

Cheap switches may say they run at 100Mb/s but you get what you pay for.