sql>alter system set log_archive_dest=’+LWK/archivelog’ scope=spfile sid=’*';

然后关闭两个实例，启动实例，更改数据库为归档模式：

sql>shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
sql>startup mount;
ORACLE instance started.

Total System Global Area 1258291200 bytes
Fixed Size1978336 bytes
Variable Size352325664 bytes
Database Buffers889192448 bytes
Redo Buffers14794752 bytes
Database mounted.
sql>alter database archivelog;

Database altered.

sql>alter database open;

sql>archive log list;
Database log modeArchive Mode
Automatic archivalEnabled
Archive destination/opt/oracle/archive
Oldest online log sequence83
Next log sequence to archive84
Current log sequence84

接下来启动另外一个节点，完成归档模式的变更过程。

在 RAC环境下，归档路径的选择是值得斟酌的，如果使用共享的归档目录作为归档路径，则可以减少备份时的复杂性。如果使用独立的目录，则备份时需要进行特殊处理。