[CentOS] network copy performance is poor (rsync) - debugging suggestions?

[Gordon Messmer]

On 01/29/2015 09:09 AM, Les Mikesell wrote:
>> our investigation showed the rsync process even with all switches
>> we found has to "open" the file a bit before it copies it
> Rsync is going to read the directory tree first, then walk it on
> both sides comparing timestamps (for incrementals) and block
> checksums.

Note that rsync only opens files and performs block checksums if the 
source and destination modification times and sizes don't match.

You should not see most files opened during an incremental copy, unless 
one of the filesystems is MS-FAT, where modification time has a 2 second 
resolution, and it may not be possible to preserve a timestamp exactly 
during a copy.