1. primary server
确认是主: primary
select database_role from v$database;

alter database commit to switchover to physical standby with session shutdown;
shutdown immediate;
startup nomount;
alter database mount standby database;

2.standby server
select database_role from v$database;
physical standby
alter database commit to switchover to primary with session shutdown;

alter recover database managed standby database disconnect from session;
shutdown immediate;
startup;

select database_role from v$database;
select switchover_status from v$database;