仔細看了問題，發現sdh_ora_29241.trc這個dump檔案在我重新開機伺服器之前一直在擴大，然後是本地能連上資料庫，二通過監聽則不能連接配接資料庫。重新開機後正常。
alert.log如下：
Wed Dec 15 08:02:41 2010
Errors in file /oracle/app/oracle/admin/sdh/udump/sdh_ora_29241.trc:
---此檔案sdh_ora_29241.trc有3G大
ORA-12570: TNS:packet reader failure
Wed Dec 15 09:17:25 2010
Failure to extend rollback segment 27 because of 3113 conditionFULL status of rollback segment 27 set.
Wed Dec 15 09:38:52 2010
Failure to extend rollback segment 30 because of 3113 conditionFULL status of rollback segment 30 set.
故障記錄于此，待分析。。。
--------------------------------------------
由于此問題現象沒找到對應的故障解決方案，咨詢oracle，提出了監控方案，記錄如下，待下次故障發生
Can you able to reproduce this issue If yes please do provide the following,
Please set the following parameter in sqlnet.ora (server / client side) and then reproduce the error.
To enable SQL*Net tracing, add the following lines to $ORACLE_HOME/network/admin/sqlnet.ora on the machine:
Server (add to server’s sqlnet.ora):
trace_level_server=16
trace_directory_server=*
trace_file_server=*
(or)
Client (add to sqlnet.ora):
trace_level_client=16
trace_directory_client=*
trace_file_client=*
and upload the trace file