Alessandra Forti (University of Manchester (GB))
In this paper we will present the efforts carried out in the UK to fix the WAN transfers problem highlighted by the ATLAS sonar tests. We will present the work done at site level, the monitoring tools at local level on the machines (ifstat, tcpdump, netstat...), between sites (iperf) and at FTS level monitoring. We will describe the effort to setup a mini-mesh to simplify the sonar tests setup separating the FTS layer from the transport layer. We will present the improvements and optimizations carried out by sites on kernel parameters and bonding setup at machine and switch level the attempt to understand differences between sites rates despite similar setup and most of all the asymmetric traffic obesrved at some sites. We will also describe work on the FTS channel organisation and configuration that has been carried out in parallel and talk about the opportunity and plans to upgrade the site insfrastructure to 10Gbps.