Hi, is this help ful to you.....
copy and paste from metalink...
The purpose of this note is to explain to you why you are getting very large log/trace files, e.g. nmi.log and how you can get around that.
Why are you getting large log/trace files:
You upgraded the database from 7.3.4 to 8.1.5. You are using 815 agent with OEM 2.0.4. Some of the log or trace files, e.g. Nmi.log keeps expanding and filling the hardware drive.
There are many reasons for this problem. However, you need to consider the following reasons.
Usually after the agent writes something in nmi.log, dbsnmpc.log, dbsnmpw.log, dbsnmpc.trc, dbsnmpw.trc, oratcl.trc, it should close the file to make a cleanup.
However, if you are facing that problem, you can do the following to avoid it:
1) Stop the agent
2) Remove and/or copy log and trace files,
3) Restart agent
Another reason for that problem that you may need to consider is if the listener.ora includes EXTPROC1, the agent keeps log and trace files locked and you will not be able to cleanup while running. External procedure (EXTPROC)
causes that problem in version 8.0.5 (bug 908515). This problem occurs when you have two Oracle homes, one for 7.3.4 and another for 8.0.5. The agent and the listener are in the 8.0.5 home. The agent is unable to connect to the
7.3.4. OEM events will not function because the database will always show as DOWN, thus UP DOWN events will always fail with the RED flag, others will fail.
If the listener.ora is causing the large nmi.log, you need to do the following:
1) remove the following standard entries from the listener.ora
Once these entries have been removed and the listener has been restarted the errors will no longer appear in the .log files, but you will not be able to use external procedures and thus oracle cartridges. Agent 815 does not cause this problem when used with multiple oracle homes and external procedures.
There might be other reasons for large log files, e.g. nmi.log.
Just consider the above two workarounds if applicable.
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Stopping both the intelligent agent and the listener seemed to do the trick, thanks. I was then able to delete the file and restart the services.
I haven't had chance to investigate why the file was getting so large, but when I do, I'll let you know.