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This article introduces the relevant knowledge of "the reasons and solutions for the inability to collect awr reports due to the non-automatic creation of oracle snapshots". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Today, it is found that one node of the customer oracle rac environment cannot automatically create snapshots, resulting in no way to collect awr reports, but can only create snapshots manually. After information exclusion, it is found that one node has fewer processes than two nodes, and it is found that one node has no mmon and mmnl processes. These two processes are the processes that automatically create snapshots. These processes are oracle non-core processes that can be kill-killed. Oracle will automatically start the process. And automatic maintenance. But the two processes of the client here are completely dead. Find the cause of the resolution in oracle mos.

1. About the MOS Document of the MMON and MMNL background processes:

APPLIES TO:

Oracle Database-Enterprise Edition-Version 11.2.0.4 to 11.2.0.4 [Release 11.2]

Information in this document applies to any platform.

SYMPTOMS

Due to other reasons, the MMON process died and subsequent AWR reports are therefore not getting generated.

The MMON process should automatically be respawned but it is not.

CAUSE

MMON/MMNL not being respawned or recreated is due to:

Unpublished bug: Bug 19565533-MMON/MMNL CAN NOT BE AUTOMATICALLY RESTARTED AFTER KILLED

The issue only occurs on 11.2.0.4 and is a regression of the fix for

Apply interimAs a workaround, you can respawn the MMON process by next methods:

Restart the database instance

-OR-

Set the instance to "restricted session" mode and then bring it back to normal mode using following commands as SYSDBA:

Alter system enable restricted session

Alter system disable restricted session

Reason. It is bug that causes the mmon and mmnl processes to die.

Solution:

1. Restart the instance

2. Set the database to restricted session mode without restarting the instance

Alter system enable restricted session

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