MMNL进程与ORA-07445 ktsmg_get_threshold问题

今天测试一个数据库出现了一点小问题。从警告信息看，错误提示如下： 
Sun Oct 15 11:07:40 2006
Errors in file /opt/oracle/admin/alexhell/bdump/eygle_mmnl_2031.trc:
ORA-07445: exception encountered: core dump [ktsmg_get_threshold()+819] [SIGFPE] [Integer divide by zero] [0x8CD532B] [] []
Sun Oct 15 11:12:59 2006
Restarting dead background process MMNL
MMNL started with pid=13, OS id=2043
MMNL absent for 3259 secs; Foregrounds taking over
MMNL absent for 3259 secs; Foregrounds taking over
MMNL absent for 3259 secs; Foregrounds taking over
Sun Oct 15 11:13:02 2006
Errors in file /opt/oracle/admin/alexhell/bdump/eygle_mmnl_2043.trc:
ORA-07445: exception encountered: core dump [ktsmg_get_threshold()+819] [SIGFPE] [Integer divide by zero] [0x8CD532B] [] []
Sun Oct 15 11:18:18 2006
Restarting dead background process MMNL
MMNL started with pid=13, OS id=2055
MMNL absent for 3580 secs; Foregrounds taking over
MMNL absent for 3580 secs; Foregrounds taking over
MMNL absent for 3580 secs; Foregrounds taking over




    错误提示每5分钟出现一次，也就是说MMNL进程每5分钟尝试一次重新启动，然后失败。

    进一步检查发现UNDO表空间处于脱机状态，将该表空间Online之后，问题消除。

SQL> select file_id, file_name, tablespace_name, online_status from dba_data_files;

FILE_ID FILE_NAME                                          TABLESPACE_NAME                ONLINE_
------- -------------------------------------------------- ------------------------------ -------
      1 /opt/oracle/oradata/eygle/system01.dbf            SYSTEM                        SYSTEM
      2 /opt/oracle/oradata/eygle/undotbs01.dbf            UNDOTBS1                      OFFLINE
      3 /opt/oracle/oradata/eygle/sysaux01.dbf            SYSAUX                        ONLINE
      4 /opt/oracle/oradata/eygle/users01.dbf              USERS                          ONLINE
      5 /opt/oracle/oradata/eygle/system02.dbf            SYSTEM                        SYSTEM

SQL> alter database datafile 2 online;

Database altered.

SQL> select file_id, file_name, tablespace_name, online_status from dba_data_files;

FILE_ID FILE_NAME                                          TABLESPACE_NAME                ONLINE_
------- -------------------------------------------------- ------------------------------ -------
      1 /opt/oracle/oradata/eygle/system01.dbf            SYSTEM                        SYSTEM
      2 /opt/oracle/oradata/eygle/undotbs01.dbf            UNDOTBS1                      ONLINE
      3 /opt/oracle/oradata/eygle/sysaux01.dbf            SYSAUX                        ONLINE
      4 /opt/oracle/oradata/eygle/users01.dbf              USERS                          ONLINE
      5 /opt/oracle/oradata/eygle/system02.dbf            SYSTEM                        SYSTEM