Caveats when upgrading from Java 6 to Java 7 on hundreds of production servers [closed]

I can't comment on the codebase running within Tomcat but we're running Tomcat 6 with Java 7 and there are no issues; the developers, however, need to conduct their own readiness tests. There a few housekeeping items to consider though such as

• Custom certificates in the keystore that need to be transferred to the new JDK
• Custom entries in the java.policy file? E.g. JMX options
• Custom entries in java.security e.g. we adjust the DNS TTL in this file

Configuration management tools like Chef/Puppet can assist in this regard.

I've never had issues with Java 6 to Java 7... I typically did the move via the OpenJDK packaging to make sure /etc/alternatives and all symlinks were updated properly. You're going to have a much bigger issue with the mechanics of the EL5 to EL6 move, though.