ARC1: Thread not mounted lead to database not mounting

今天在啟動資料庫的時候，發現database起不來了，停在了nomount狀態，檢查alert.log
ARCH: STARTING ARCH PROCESSES
ARC0 started with pid=8
ARC0: Archival started
ARC1 started with pid=9
ARC1: Archival started
Fri Jun 25 00:07:52 2004
ARCH: STARTING ARCH PROCESSES COMPLETE
Fri Jun 25 00:07:52 2004
ARC1: Thread not mounted Fri Jun 25 00:07:52 2004
ARC0: Thread not mounted Fri Jun 25 00:07:54 2004
ARC0: Thread not mounted
不知道是什麼原因，資料庫停在了nomount狀態，後來
sql> alter database mount ;
sql> alter database open;
問題解決了。
metalink原因如下：

THE INFORMATION IN THIS ARTICLE APPLIES TO:
          Oracle Server - Enterprise Edition - Version: 9.2.0.4
          This problem can occur on any platform.
SYMPTOMS:
        While doing the startup of the database it simply hangs at the mount stage.
CAUSE:
          From the Alert.log
=============
ARCH: STARTING ARCH PROCESSES
ARC0 started with pid=8
ARC0: Archival started
ARC1 started with pid=9
ARC1: Archival started
Fri Jun 25 00:07:52 2004
ARCH: STARTING ARCH PROCESSES COMPLETE
Fri Jun 25 00:07:52 2004
ARC1: Thread not mounted Fri Jun 25 00:07:52 2004
ARC0: Thread not mounted Fri Jun 25 00:07:52 2004

NOTE: This can happen if multiple archive processes are running. A lock conflict may result. This is not considered a bug within development.
FIX:
Open another sql*plus session
Login as sysdba
Shutdown abort
Startup