问题描述：
在数据库运行过程中发现两次 smon 进程僵死导致的数据库down机。 在这个时候， 连接数 一次为400，一次为141. 出现这样的情况的时候， sqlplus /nolog 然后 conn / as sysdba 无响应。
数据库服务器配置为 linux redhat 64位 内存 32g ， oracle 为11203. sga分配12g。大家帮忙看看错误原因。
alert中的描述如下
======================7-10================================
Thu Jul 10 14:02:36 2014
Errors in file /oracle/diag/rdbms/app/app/trace/app_smco_34722.trc (incident=537285):
ORA-00445: background process "W009" did not start after 120 seconds
Incident details in: /oracle/diag/rdbms/app/app/incident/incdir_537285/app_smco_34722_i537285.trc
Dumping diagnostic data in directory=[cdmp_20140710140240], requested by (instance=1, osid=34722 (SMCO)), summary=[incident=537285].
Thu Jul 10 14:02:42 2014
Thu Jul 10 14:03:36 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:04:36 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:06:07 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:07:07 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:07:13 2014
Errors in file /oracle/diag/rdbms/app/app/trace/app_smco_34722.trc (incident=537286):
ORA-00445: background process "W004" did not start after 120 seconds
Incident details in: /oracle/diag/rdbms/app/app/incident/incdir_537286/app_smco_34722_i537286.trc
Thu Jul 10 14:08:38 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:09:18 2014
Errors in file /oracle/diag/rdbms/app/app/trace/app_smco_34722.trc (incident=537287):
ORA-00445: background process "W005" did not start after 120 seconds
Incident details in: /oracle/diag/rdbms/app/app/incident/incdir_537287/app_smco_34722_i537287.trc
Thu Jul 10 14:09:39 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:11:09 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:11:38 2014
Thu Jul 10 14:12:09 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:13:40 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:14:40 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:16:11 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:17:11 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:18:42 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:19:28 2014
Thu Jul 10 14:19:43 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:21:14 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:22:14 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:23:45 2014
PMON failed to acquire latch, see PMON dump
Thu Jul 10 14:28:35 2014
============================================================
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Sun Aug 03 23:03:42 2014
Errors in file /oracle/diag/rdbms/app/app/trace/app_smco_5482.trc (incident=681013):
ORA-00445: background process "W000" did not start after 120 seconds
Incident details in: /oracle/diag/rdbms/app/app/incident/incdir_681013/app_smco_5482_i681013.trc
Sun Aug 03 23:03:44 2014
Dumping diagnostic data in directory=[cdmp_20140803230344], requested by (instance=1, osid=5482 (SMCO)), summary=[incident=681013].
Sun Aug 03 23:07:32 2014
Errors in file /oracle/diag/rdbms/app/app/trace/app_smco_5482.trc (incident=681014):
ORA-00445: background process "W002" did not start after 120 seconds
Incident details in: /oracle/diag/rdbms/app/app/incident/incdir_681014/app_smco_5482_i681014.trc
Sun Aug 03 23:21:07 2014
Errors in file /oracle/diag/rdbms/app/app/trace/app_qmnc_5253.trc (incident=681197):
ORA-00445: background process "q002" did not start after 120 seconds
Incident details in: /oracle/diag/rdbms/app/app/incident/incdir_681197/app_qmnc_5253_i681197.trc
Sun Aug 03 23:23:20 2014
Errors in file /oracle/diag/rdbms/app/app/trace/app_qmnc_5253.trc (incident=681198):