C:\Users\TianPan>sqlplus / as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Sat Feb 28 10:08:35 2015

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Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> ARCHIVE LOG LIST
Database log mode No Archive Mode
Automatic archival Disabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 83
Current log sequence 85
SQL> select log_mode from v$database;

LOG_MODE
------------
NOARCHIVELOG

SQL> ALTER DATABASE ARCHIVELOG;
ALTER DATABASE ARCHIVELOG
*
ERROR at line 1:
ORA-01126: database must be mounted in this instance and not open in any
instance

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.

启动到mount状态：

SQL> startup mount
ORACLE instance started.

Total System Global Area 1071333376 bytes
Fixed Size 1375792 bytes
Variable Size 637534672 bytes
Database Buffers 427819008 bytes
Redo Buffers 4603904 bytes
Database mounted.
SQL> ALTER DATABASE ARCHIVELOG;

Database altered.

SQL> ARCHIVE LOG LIST
Database log mode Archive Mode
Automatic archival Enabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 84
Next log sequence to archive 86
Current log sequence 86
SQL> ALTER DATABASE OPEN;

Database altered.

SQL> SELECT LOG_MODE FROM V$DATABASE;

LOG_MODE
------------
ARCHIVELOG

SQL>

类似的，反向操作（归档模式->非归档模式）的命令是类似的，在mount状态下执行：