I have been testing globus-url-copy between two
systems in a node. I tested with no parallel (i.e with
out -p option), and, tried with -p 2 and -p 4. I dont
see any difference in transmission times?
parallel tcp streams is a network optimization when transmitting data over networks where packets
are lost. it doesn't necessarily translate into higher throughput over all networks.
When I use -p option with globus-url-copy,
1) will there be multiple ftp processes running on
receiving or sending system (checking with ps -ef)?
No, i think you are thinking of server striped transfer. no matter what the parallel streams count,
they are formed between 2 end points.
2) Will there be any noticable change in transmission
time before and after using -p option?
often times yes, but it depends on your network.
3) when I ftp a directory with 4 files in it, and use
-p 4 option , then will these 4 files ftp'ed at same
time with 4 threads?
no. That is not how parallel streams work. Parallel streams just break 1 logical pathway into
serveral logical pathways to lessen the penalty of a dropped TCP packet. What you are talking about
here is known as 'client side striping'.
Please help with my doubts?
Seshachalapathi
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