KEBM: MMON action policy violation. 'Flashback Archive RAC Health Check' 
 viol=0; err=8181
 error 8181 detected in background process
 OPIRIP: Uncaught error 447. Error stack:
 ORA-00447: fatal error in background process
 ORA-08181: specified number is not a valid system change number
 ORA-12751: cpu time or run time policy violation

经过查询，此问题为ORACLE 一个BUG引起，BUG号为：10207092，影响的版本为：11.1.0.7（正是我们数据库的版本）和11.2.0.2

MMON进程解释：

MMON:Manageability Monitor Process
 
Performs or schedules many manageability tasks
 
MMON performs many tasks related to manageability, including taking Automatic Workload Repository snapshots and performing Automatic Database Diagnostic Monitor analysis.
 
 
 
以下是metalink上的说明：
 
Bug 10207092  MMON may repeatedly fail with ORA-447 / ORA-12751
 This note gives a brief overview of bug 10207092. 
 The content was last updated on: 14-AUG-2012
 Click here for details of each of the sections below.
Affects:
Product (Component)
Oracle Server (Rdbms)
Range of versions believed to be affected
Versions >= 11 but BELOW 12.1
Versions confirmed as being affected
11.2.0.2
11.1.0.7
Platforms affected
Generic (all / most platforms affected)
Fixed:
This issue is fixed in
12.1 (Future Release)
11.2.0.3 (Server Patch Set)
11.2.0.2.7 Patch Set Update
11.2.0.2 Bundle Patch 2 for Exadata Database
11.2.0.2 Patch 14 on Windows Platforms
Symptoms:
Related To:
Error May Occur
Unwanted or Excess Trace / Alert messages
ORA-12751 / ORA-447
Job Queues
Description
Scheduler code in MMON suppresses an error which can result in an MMON 
dump.
eg:
 KEBM: MMON action policy violation. 'Flashback Archive RAC Health Check' 
 viol=0; err=8181
 error 8181 detected in background process
 OPIRIP: Uncaught error 447. Error stack:
 ORA-00447: fatal error in background process
 ORA-08181: specified number is not a valid system change number
 ORA-12751: cpu time or run time policy violation
 
Rediscovery Notes:
  MMON keeps failing with ORA-12751 and ORA-447 on the error stack 
 
Workaround
 None
 
Please note: The above is a summary description only. Actual symptoms can vary. Matching to any symptoms here does not confirm that you are encountering this problem. For questions about this bug please consult Oracle Support.
References
Bug:10207092 (This link will only work for PUBLISHED bugs)
Note:245840.1 Information on the sections in this article