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org.apache.oodt.cas.protocol.exceptions.ProtocolException: Downloads appear to be
hanging . . . aborting wait . . . waited for 15 minutes

Packet drop/loss

$ tc qdisc change dev eth0 root netem loss 1%

Limited performance variation was observed for packet loss < 8% after which the transfer time significantly increased. For induced packet loss > 64%, PushPull generated the following error message:

org.apache.oodt.cas.pushpull.exceptions.RemoteConnectionException:
[ProtocolHandler]

Image Added

Modified TCP window

A single file of 1024MB was downloaded using PushPull using different TCP window sizes. There is the option to enable/disable TCP window scaling in the configuration file /etc/sysctl.conf and to set the maximum transfer window under LINUX. The file is then reloaded to update the parameters using

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The parameters in /etc/sysctl.conf which were modified are (e.g.):

net.core.rmem_max
net.core.wmem_max
net.core.rmem_default
net.core.wmem_default

A maximum transfer rate of ~20.1MB/s is achieved for TCP window sizes > 2048 Bytes. The smallest window size found for PushPull to be in an operational state was 256 Bytes giving an average transfer rate of ~11.2MB/s.

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