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Hi all,

I hope this is the right list for discussion of this topic...

It appears that Scientific Linux is used by many science communities,
but in particular by the HEP community.  The science community often has
significant bulk data movement requirements that are outside the
capabilities of the default network tuning parameters of most Linux
distributions.

Would the Scientific Linux community consider changing the network
tuning defaults for future releases?

ESnet maintains a site that explains network performance tuning and how
to increase network performance - please see http://fasterdata.es.net/

However, we have recently seen several sites where the first thing that
is needed is to change the network stack parameters so that
high-performance wide-area data transfers are possible.

Note that with today's TCP autotuning and modern congestion recovery
algorithms, one need not set up particular TCP parameters on a
per-destination basis.  One need only give TCP autotuning enough buffer
space to do its work and ensure that a modern congestion recovery
algorithm is used (the default in Linux 2.6 has been cubic for a while,
though 2.6.18 has bugs in cubic that significantly damage performance so
for 2.6.18 one should use htcp instead).

Please see http://fasterdata.es.net/tuning.html and
http://fasterdata.es.net/TCP-tuning/linux.html for linux-specific
information.

Thoughts?  Comments welcome....

Many thanks,


		--eli


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Eli Dart                                            NOC: (510) 486-7600
ESnet Network Engineering Group                          (800) 333-7638
Lawrence Berkeley National Laboratory
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