hi,
After reading next post: https://issues.jenkins-ci.org/browse/JENKINS-12037 and some others,
we assumed that upgrading our Jenkins 1.443 and Tomcat 6.0.29 will solve "SEVERE: I/O error in channel" and "java.io.IOException: Unexpected termination of the channel" failures in catalina.out file,
so today we have upgraded them to Jenkins 1.462 and tomcat 7.0.27, but we still get these failures.

We have set next in $CATALINA_HOME/conf/server.xml file:
connectionTimeout="60000"
disableUploadTimeout="false"
connectionUploadTimeout="60000"

Also, we have set "In demand delay" and "Idle delay" to 3 min in all our nodes.

What else can be done???