问题描述
当使用SQL进行备份操作时，出现下面的错误，提示不能启动在线备份，具体错误信息如下：
SYS@orcl _SQL>alter tablespace users begin backup;
alter tablespace users begin backup
*
ERROR at line 1:
ORA-01123: cannot start online backup; media recovery not enabled解决办法
出现此种问题的原因是数据库处于非归档模式，不能在线进行备份，只能在数据库处于归档模式时，方可执行在线SQL备份，具体演示如下：
SYS@orcl _SQL>archive log list;
Database log mode No Archive Mode----->数据库处于非归档模式
Automatic archival Disabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 106
Current log sequence 108
SYS@orcl _SQL>shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SYS@orcl _SQL>startup mount
ORACLE instance started.
Total System Global Area 778387456 bytes
Fixed Size 1374808 bytes
Variable Size 520095144 bytes
Database Buffers 251658240 bytes
Redo Buffers 5259264 bytes
Database mounted.
SYS@orcl _SQL>alter database archivelog;---->启用数据库归档模式
Database altered.
SYS@orcl _SQL>alter database open;
Database altered.
SYS@orcl _SQL>alter tablespace users begin backup;
Tablespace altered.
SYS@orcl _SQL>host copy E:APPALEN.LIUORADATAORCLUSERS01.DBF e:USERS01.DBF
已复制 1 个文件。
SYS@orcl _SQL>alter tablespace users end backup;
Tablespace altered.
SYS@orcl _SQL>