在只读模式下，数据文件及联机日志文件都禁止写操作。不过允许执行数据库恢复及其他不会产生回滚的操作。
数据库关闭的情况下
[oracle@prod1 ~]$ sqlplus / as sysdba SQL*Plus: Release 11.2.0.1.0 Production on Sun Feb 22 19:07:12 2015 Copyright (c) 1982, 2009, Oracle. All rights reserved. Connected to an idle instance. idle> startup open read only; ORACLE instance started. Total System Global Area 891383808 bytes Fixed Size 1340104 bytes Variable Size 658509112 bytes Database Buffers 226492416 bytes Redo Buffers 5042176 bytes Database mounted. Database opened. idle> select open_mode from v$database;OPEN_MODE --------------------READ ONLY
mount状态下
idle> alter database open read only; Database altered.
重新恢复到读写状态
idle> shutdown immediate; Database closed.Database dismounted.ORACLE instance shut down.idle> startup mount; ORACLE instance started.Total System Global Area 891383808 bytesFixed Size 1340104 bytesVariable Size 658509112 bytesDatabase Buffers 226492416 bytesRedo Buffers 5042176 bytesDatabase mounted.idle> alter database open read write; Database altered.
在只读模式下，数据文件及联机日志文件都禁止写操作。不过允许执行数据库恢复及其他不会产生回滚的操作。
数据库关闭的情况下
[oracle@prod1 ~]$ sqlplus / as sysdba SQL*Plus: Release 11.2.0.1.0 Production on Sun Feb 22 19:07:12 2015 Copyright (c) 1982, 2009, Oracle. All rights reserved. Connected to an idle instance. idle> startup open read only; ORACLE instance started. Total System Global Area 891383808 bytes Fixed Size 1340104 bytes Variable Size 658509112 bytes Database Buffers 226492416 bytes Redo Buffers 5042176 bytes Database mounted. Database opened. idle> select open_mode from v$database;OPEN_MODE --------------------READ ONLY
mount状态下
idle> alter database open read only; Database altered.
重新恢复到读写状态
idle> shutdown immediate; Database closed.Database dismounted.ORACLE instance shut down.idle> startup mount; ORACLE instance started.Total System Global Area 891383808 bytesFixed Size 1340104 bytesVariable Size 658509112 bytesDatabase Buffers 226492416 bytesRedo Buffers 5042176 bytesDatabase mounted.idle> alter database open read write; Database altered.
