SQL> conn /as sysdba Connected to an idle instance. SQL> startup ORACLE instance started. Total System Global Area 276824064 bytes Fixed Size 778736 bytes Variable Size 137371152 bytes Database Buffers 138412032 bytes Redo Buffers 262144 bytes ORA-01102: cannot mount database in EXCLUSIVE mode SQL> shutdown immediate ORA-01507: database not mounted ORACLE instance shut down.
GOOGLE一下，发现是lk<SID>文件造成的，该文件位于ORALCE_HOME下的dbs目录下，马上检查该文件：
未发现该文件
关于该错误更详细的介绍如下：原文链接：http://www.hellodba.com/cases/case-unexception_down.htm
还有些原因是内存未释放，信号量的问题，直接重启机器，问题解决