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Don Burleson Blog 







ORA-00445 background process PMON did not start tips

Oracle Tips by Burleson Consulting

February 11, 2010

Question:  At the startup command, we are facing ORA-00445 error PMON does not start even after 120 sec at the time of instance starting up.  How do I resolve the ORA-00445 error and restart PMON.

Answer:  The docs note that the ORA-00445 error happens when a background process cannot start running:

ORA-00445: background process "string" did not start after string seconds

Cause: The specified process did not start after the specified time.

Action: Ensure that the background did not die and leave a trace file.

You start troubleshooting an ORA-00445 error by examining your alert log and check for trace files in the bdump (background_dump_dest) directory.

I have seen the ORA-00445 because the OS is still holding the SGA RAM after a previous crash.

First, run an “ipcs –pmb” command and see if you have leftover RAM segments from the last instance.  If you find held RAM, run the ipcrm command to remove the segments.  Here is how to check for held SGA RAM on the OS.

If PMON fails on startup, it’s almost always because of one of these conditions:

  1. Leftover memory segments from a previous instance crash.

  2. Incorrect environment parameter settings in SQL*Plus ($ORACLE_HOME, $ORACLE_SID).

  3. Permission issues with the Oracle executables.

  4. Not enough CPU/RAM resources for the startup to complete. 

In any case, the associated trace file will give you the exact reason for the ORA-00445 error.





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