[CentOS] Network Performance Update

Sun May 6 06:12:16 UTC 2018
Gordon Messmer <gordon.messmer at gmail.com>

On 05/04/2018 07:56 AM, Chris Olson wrote:
> Bottom Line: Mystery partially solved. What is left is why the
> /dev/null destination for the data does not work.
> Attempting Transfer Of dd Created Output To /dev/null
> -------------------------------------------------------------
> ftp>
> ftp> put "|dd if=/dev/zero bs=32768 count=8000" /dev/null
> local: |dd if=/dev/zero bs=32768 count=8000 remote: /dev/null
> 227 Entering Passive Mode (192,168,1,101,27,154)
> 500 OOPS: ftruncate
> dd: writing `standard output': Broken pipe

It looks like the FTP server is attempting to use ftruncate() on the 
destination file, and that call fails when the destination file is 
/dev/null.  The server then closes the connection, and dd reports that 
it cannot write to its stdout fd, and the error reported is EPIPE.

You might not get that error with a different ftp server, and there are 
no shortage of options there.  However, you're probably just as well off 
with something that has less overhead.   You can use "nc" (netcat) for 
this task, or iperf as was suggested earlier.