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?
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
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
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.
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.
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
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.
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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