What you at least should know about Node Manager by Cato Aune

Posted: May 2, 2015 in WebLogic
Tags: , , , , , ,


clip_image002Node Manager is an important utility when running WebLogic in a production environment. Most people pay little attention to the Node Manager, but when problem arises, it is a little bit late to figure out what Node Manager is and what it does.

This article is not a full introduction to Node Manager, but will describe some best practices for common real life situations and issues, and share some tips and tricks gathered over the years.

If you would like a full introduction to Node Manager first, with all the nice diagrams showing how everything is connected, then you should look at the official documentation, which by the way are getting pretty good, before coming back to read the rest of this article -  http://docs.oracle.com/middleware/1213/wls/NODEM/overview.htm#NODEM112

So, what is Node Manager?

Node Manager is a utility used to start, stop and restart WebLogic and Coherence servers on the host Node Manager is installed. Since you could connect to Node Manager from a remote server, you will use Node Manager on the remote server as a tool to remotely start and stop a WebLogic instance.

There are two version of Node Manager, the Java version and the script based version. Unless you have very specific requirements, use the Java version, which also happens to be the one that most people think of when they talk about Node Manager. This article will be about the Java version, but if you want to know more about the difference of the two versions, have a look at the official documentation – http://docs.oracle.com/middleware/1213/wls/NODEM/overview.htm#NODEM114

Per host vs per domain Node Manager

Up until WebLogic 12.1.2 the default was one Node Manager per host. It was possible to do it otherwise, but it was not documented very well.

From 12.1.2 the default is one Node Manager per domain, and the configuration and logs are now located under $DOMAIN_HOME/nodemanager instead of under wlserver_10.3/common/nodemanager

It is still possible to have one Node Manager per host, for those who prefers that.

If you are using Node Manager for an earlier release (before 12.1.2) or just want to stick with one Node Manager per host, you should consider moving the configuration and log files away from wlserver_10.3/common/nodemanger and have them outside the $ORACLE_HOME. There are several reasons for that, one important reason is to keep configuration files away from the binaries, so the configuration is kept in case an upgrade overwrites everything under wlserver_10.3/common/nodemanager. Another important reason is that you want to have logfiles in a location that you monitor for disk space, since logfiles tends to grow, and you might not have taken that into consideration when deciding how much space you needed for the installation.

ne special case where you actually needed more than one Node Manager for a host in 11g was when you followed the Enterprise Deployment Guide (EDG) for SOA. In an enterprise setup, the Administration Server is installed in a different $DOMAIN_HOME than the managed servers. This makes it easier to start the Administration Server on another host in case of a host failure (Administration Server domain directory should be on a SAN or a shared disk).

The reason for using one Node Manager for the Administration Server domain directory and one for the Managed Servers domain directory is that the nodemanager.domains file in 11g could only can have one path per domain.

In 12c there is possible to have one primary domain path and several alternate domain paths for each domain in nodemanager.domains, so it should be enough with one Node Manager per domain from 12.1.3 Read the complete article here.

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