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)


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