primary>startup
ORACLE instance started.

Total System Global Area  281018368 bytes
Fixed Size                  2020160 bytes
Variable Size             100666560 bytes
Database Buffers          171966464 bytes
Redo Buffers                6365184 bytes
Database mounted.
Database opened.
某一远程会话终端启动数据库，给人一种假象，数据库已经打开，但是日志中却已经报错了，错误信息如下：
ARC0: Failed to archive thread 1 sequence 45 (4)
ARCH: Archival stopped, error occurred. Will continue retrying
Thu Mar 27 15:27:54 2014
ORACLE Instance orcl - Archival Error
Thu Mar 27 15:27:54 2014
ORA-16014: log 1 sequence# 45 not archived, no available destinations
ORA-00312: online log 1 thread 1: '/u01/app/oradata/orcl/redo01.log'
Thu Mar 27 15:27:54 2014
Errors in file /u01/app/admin/orcl/bdump/orcl_arc0_2955.trc:
ORA-16014: log 1 sequence# 45 not archived, no available destinations
ORA-00312: online log 1 thread 1: '/u01/app/oradata/orcl/redo01.log'
错误信息提示：archive log 无法归档，而且报错信息看出是  standby01.log该日志文件被损坏了。
primary>alter database clear unarchived logfile group 1;         --将未归档的内容清除     
Database altered.
primary>shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
primary>startup
ORACLE instance started.

Total System Global Area  281018368 bytes
Fixed Size                  2020160 bytes
Variable Size             104860864 bytes
Database Buffers          167772160 bytes
Redo Buffers                6365184 bytes
Database mounted.
Database opened.

在终端执行语句时，眼睛一眨不眨的盯着日志信息，最后显示没有报错。
批注：平时做实验模拟练习时，多打开几个终端，养成查看日志信息的习惯，不至于以后操作生产环境下的数据库时手忙脚乱。也许客户端没有报错，但是日志已经提示出错了。