May 23, 2016

Restart MMON process without bouncing the database

Filed under: Uncategorized — srivenu @ 4:40 pm

Today one of my team members was mentioning to me that AWR snapshot’s were not getting generated in one of his instance. It seems that MMON process crashed with ORA-600. As a workaround, he created a cron job to manually generate AWR snapshots. Looks like he couldn’t find the solution for the problem and was going to bounce the instance to fix the issue. I had experience the issue of MMON crash a few times in the past and i used this workaround to fix it. Thought i would share it for the benefit of others.

Run the following commands from a sqlplus session and this should start a new MMON process.

alter system enable restricted session;

alter system disable restricted session;

(For junior DBA’s, be very careful and don’t do this on a critical production system. Even though you put the system in restricted mode only for a brief duration, be aware of the restrictions of restricted mode – refer to “Restricting Access to an Instance at Startup” in Oracle Database Administrator’s Guide)



  1. Thanks for the details. I was facing issue on my critical production system and sort it out by using below steps. sharing with you guys may be It help you..
    check status of mmon process, in my case i found not running.
    $ ps -ef |grep mmon
    SQL> grant restricted session to public;
    SQL> alter system enable restricted session;
    SQL> alter system disable restricted session;
    SQL> revoke restricted session from public;
    $ ps -ef |grep mmon

    Comment by Asad — February 7, 2017 @ 10:34 pm | Reply

  2. Thanks, worked for me 🙂

    Comment by ManPau — October 4, 2017 @ 1:08 am | Reply

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