4.1. Tuning the App Trace Roll

This section discusses how to tune the App Trace Roll to fit your needs.

The App Trace Roll is tuned through replacing the XML node file app-trace-client.xml.

First, create a replace-app-trace-client.xml file:

# cd /home/install/site-profiles/4.1/nodes/
# cp /home/install/rocks-dist/lan/*/build/nodes/app-trace-client.xml replace-app-trace-client.xml

There are 4 tunable values: COLLECTHOSTLOCAL, COLLECTHOSTSDSC, TRACEDIR and FILESIZE.

• COLLECTHOSTLOCAL - This is the host that trace files are uploaded to when executing 'make -f /opt/app-trace/collect/Makefile local'. The default value is the private IP address of your frontend.

• COLLECTHOSTSDSC - This is the host that trace files are uploaded to when executing 'make -f /opt/app-trace/collect/Makefile sdsc'. The default value is the traces.rocksclusters.org which is a host at SDSC.

• TRACEDIR - This is the directory on the compute node where the trace file is stored. The default value is /state/partition1.

• FILESIZE - This is the maximum size of the trace file. The default value is 10% of the partition on which TRACEDIR resides.

After modifying the above values, you can apply the values to the compute nodes by rebuilding the distribution and reinstalling the compute nodes:

# cd /home/install
# rocks-dist dist
# cluster-fork '/boot/kickstart/cluster-kickstart ; exit'