This post is part of a series exploring the unique aspects and capabilities of WebSphere Liberty when running on z/OS.
We'll also explore considerations when moving from WebSphere traditional on z/OS to Liberty on z/OS.

The next post in the series is here.

To start at the beginning, follow this link to the first post.

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The next thing I looked at was the TRAS0018I message which tells you the state of tracing in the server.  You can get this message multiple times as the trace state changes for various reasons.  Of course the most recent instance of it will tell you the current state so search up from the bottom. 

In general there’s probably some minimum amount of tracing you’d want to have on all the time, just so some informational stuff gets generated that will be useful to have in looking at server output or if something goes wrong.  But I wouldn’t expect much specific detailed tracing to be on unless support has asked you to turn something on to help diagnose a problem.  And, of course, once that problem has been diagnosed you should go back and change the configuration to your normal tracing levels.  You don’t need all that chatter anymore. 

I know that seems obvious, but over the years I’ve seen logs come in for problems with totally unrelated tracing enabled that was turned on for some other problem a while back and it still spewing out, slowing things down and taking up space.  It can be easy to forget, in the frenzy of getting a problem fixed, to put tracing back the way it was. 

So what about that tracing specification?  Anything at all complex should be provided to you by support, but what is it saying?  There’s a nice article that describes the syntax and a whole bunch of other trace configuration stuff located, as I write this anyway, here:

https://openliberty.io/docs/latest/log-trace-configuration.html

Located, at present, way at the bottom of that page you can see that the specification is a series of things separated by colons.  Each one is a scope of the trace and then log level.  So you might see something like “*=info” which says to turn on information level tracing for everything.  This is a pretty common setting. 

Support might having you turn on tracing for some specific package of code, like “com.ibm.jbatch.*=finer”.  Any tracing in Java code under that package (which is probably actually several packages underneath ‘jbatch’) will get ‘finer’ level tracing. 

An explanation of ‘finer’, ‘info’, and all the other possible values should be at the link above.

The other thing you might see is something that isn’t a package name like ‘config=all’ where the ‘config’ is a group name.  When the Liberty code registers with the tracing code it can specify a group it is part of and specifying one of these group names turns on tracing for all the code, regardless of package, that is part of that group.  So there’s a bunch of config-related code whose tracing gets turned on by that group name being specified. 

You CAN dig around in the open source parts of Liberty and see all the package names and group names, but probably you’ll just want to let support figure out what they need and tell you what to enable.