單機Linux平臺Oracle 10g DataGuard Physical Standby 搭建例項(5)

SQL> select protection_mode,protection_level from v$database;

PROTECTION_MODE      PROTECTION_LEVEL

-------------------- --------------------

MAXIMUM PERFORMANCE  MAXIMUM PERFORMANCE

SQL> alter database set standby database to maximize availability;

SQL> select protection_mode,protection_level from v$database;

PROTECTION_MODE      PROTECTION_LEVEL

-------------------- --------------------

MAXIMUM AVAILABILITY RESYNCHRONIZATION

SQL> alter system switch logfile;

SQL> select protection_mode,protection_level from v$database;

PROTECTION_MODE      PROTECTION_LEVEL

-------------------- --------------------

MAXIMUM AVAILABILITY RESYNCHRONIZATION

SQL> shutdown immediate;

SQL> startup

SQL> select protection_mode,protection_level from v$database;

PROTECTION_MODE      PROTECTION_LEVEL

-------------------- --------------------

MAXIMUM AVAILABILITY RESYNCHRONIZATION

Maximum protection/AVAILABILITY/ PERFORMANCE模式必須滿足的條件

SQL> alter system set log_archive_dest_2='SERVICE=stby LGWR SYNC AFFIRM valid_for=(ONLINE_LOGFILES,PRIMARY_ROLES) DB_UNIQUE_NAME=stby' scope=spfile;

SQL> shutdown immediate;

SQL> startup mount;

SQL> alter database set standby database to maximize availability;

SQL> alter database open;

Database altered.

SQL> select protection_mode,protection_level from v$database;

PROTECTION_MODE      PROTECTION_LEVEL

-------------------- --------------------

MAXIMUM AVAILABILITY MAXIMUM AVAILABILITY

alter database set standby database to maximize performance;

提示：maximize後可跟{PROTECTION | AVAILABILITY | PERFORMANCE}，分別對應最大保護，最高可用性及最高效能。

在最大保護模式下，直接關閉備庫是不行的，如果在備庫上關閉資料庫，會有如下提示：

SQL> shutdown immediate

ORA-01154: database busy. Open, close, mount, and dismount not allowed now

在最大保護模式下，備庫是不允許關閉的，此時首先關閉主庫，然後備庫就可以順利關閉了。

注意：主庫的保護模式修改之後，備庫的模式也會改變，和主庫保持一致。