On 31 January 2013 14:38, Philipp Kern <[email protected]> wrote:

> Also you should be able to do between 100MB/s to 1GB/s on 10 GE, which is

My rule of thumb is that pumping 100 MB/s or so through the Linux
TCP/IP stack will burn a CPU, maybe half if he can use large packets.
So 1 GB/s takes 5-10 CPUs if the wire can stand it. I have not
measured the z/OS stack, but considering that he's probably using
capacity model CPUs for z/OS, that might be the choke in the path. And
it would not be the first case for network benchmarks being limited by
Linux disk I/O speed...

Since he mentioned FTP, encryption will not be the problem. Still,
with decent gear the suggested 6 MB/s for FTP is still low...
I did once work on a problem where FTP bandwidth was highly asymmetric
(get from Linux was 3 orders of magnitude faster than put from z/OS).
If such a big difference is observed in this case, I might be able to
help tune the buffers (which is harder than just making them bigger).

Rob van der Heij
Velocity Software
http://www.velocitysoftware.com/

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