head node has an extremely high load average.

[Miner, Jonathan W (US SSA)]

> How does one determine from which node the massive io requests are coming?

This falls under network monitoring.  You could use a program like "iptraf"; if you run it on the server you should be able to get it to display bytes per client, etc.

Or if your switches have snmp monitoring, you could use mrtg to graph the per port usage.  Assuming that each port maps to a single device, then you'd be able to map high usage back to the client machine.  You could also use a snmp monitoring program (Nagios is one...)  to actively alert you if usage was above a certain threshold.

https://fedorahosted.org/iptraf-ng/
http://oss.oetiker.ch/mrtg/
http://www.nagios.org/

- Jon