>+-dg`。有关如何使用从 Secrets Manager 检索到的 SSH（安全 Shell）密钥连接到 RDS 自定义实例的更多信息，请参阅[使用 SSH 连接到 RDS 自定义数据库实例](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/custom-creating.html#custom-creating.ssh)。要通过 Data Guard 命令行 (`dgmgrl`) 访问 Oracle Data Guard 代理配置，请使用以下代码。**非 CDB**$ dgmgrl RDS_DATAGUARD@RDS_CUSTOM_ORCL_D
DGMGRL for Linux: Release 19.0.0.0.0 - Production on Fri Sep 30 22:44:49 2022
Version 19.10.0.0.0
Copyright (c) 1982, 2019, Oracle and/or its affiliates. All rights reserved.
Welcome to DGMGRL, type "help" for information.
Password:
Connected to "ORCL_D"
Connected as SYSDG.
DGMGRL>
DGMGRL> show database orcl_d
Database - orcl_d
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 0 seconds ago)
Apply Lag: 0 seconds (computed 0 seconds ago)
Average Apply Rate: 11.00 KByte/s
Instance(s):
ORCL
SUCCESS
DGMGRL>
**CDB**-bash-4.2$ dgmgrl C##RDS_DATAGUARD@RDS_CUSTOM_RDSCDB_B
DGMGRL for Linux: Release 19.0.0.0.0 - Production on Wed Jan 11 20:24:11 2023
Version 19.16.0.0.0
Copyright (c) 1982, 2019, Oracle and/or its affiliates. All rights reserved.
Welcome to DGMGRL, type "help" for information.
Password:
Connected to "RDSCDB_B"
Connected as SYSDG.
DGMGRL>
DGMGRL> show database rdscdb_b
Database - rdscdb_b
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 1 second ago)
Apply Lag: 0 seconds (computed 1 second ago)
Average Apply Rate: 2.00 KByte/s
Real Time Query: OFF
Instance(s):
RDSCDB
Database Status:
SUCCESS
DGMGRL>
| 数据库管理员 |
| 通过从主节点连接到 DGMGRL 来更改日志传输设置。 | 将日志传输模式更改为 `FastSync`，对应于重做传输设置 `SYNC+NOAFFIRM`。若要确保在角色切换后具有有效的设置，请同时更改主数据库和备用数据库的设置。**非 CDB**DGMGRL>
DGMGRL> edit database orcl_d set property logxptmode=fastsync;
Property "logxptmode" updated
DGMGRL> show database orcl_d LogXptMode;
LogXptMode = 'fastsync'
DGMGRL> edit database orcl_a set property logxptmode=fastsync;
Property "logxptmode" updated
DGMGRL> show database orcl_a logxptmode;
LogXptMode = 'fastsync'
DGMGRL>
**CDB**DGMGRL> edit database rdscdb_b set property logxptmode=fastsync;DGMGRL> edit database rdscdb_b set property logxptmode=fastsync;
Property "logxptmode" updated
DGMGRL> show database rdscdb_b LogXptMode;
LogXptMode = 'fastsync'
DGMGRL> edit database rdscdb_a set property logxptmode=fastsync;
Property "logxptmode" updated
DGMGRL> show database rdscdb_a logxptmode;
LogXptMode = 'fastsync'
DGMGRL>
| 数据库管理员 |
| 将保护模式更改为 MaxAvailability。 | 通过从主节点连接到 `DGMGRL`，将保护模式更改为 `MaxAvailability`。**非 CDB**DGMGRL> edit configuration set protection mode as maxavailability;
Succeeded.
DGMGRL> show configuration;
Configuration - rds_dg
Protection Mode: MaxAvailability
Members:
orcl_a - Primary database
orcl_d - Physical standby database
Fast-Start Failover: Disabled
Configuration Status:
SUCCESS (status updated 38 seconds ago)
DGMGRL>
**CDB**DGMGRL> show configuration
Configuration - rds_dg
Protection Mode: MaxAvailability
Members:
rdscdb_a - Primary database
rdscdb_b - Physical standby database
Fast-Start Failover: Disabled
Configuration Status:
SUCCESS (status updated 57 seconds ago)
DGMGRL>
| 数据库管理员 |
### 将复制副本状态从附加更改为只读，并启用重做应用
| Task | 说明 | 所需技能 |
| --- | --- | --- |
| 停止对备用数据库进行重做应用。 | 默认情况下，只读副本是在 `MOUNT` 模式下创建的。要以只读模式打开它，首先需要通过从主节点或备用节点连接到 `DGMGRL` 来关闭重做应用。**非 CDB**DGMGRL> show database orcl_dDGMGRL> show database orcl_d
Database - orcl_d
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 1 second ago)
Apply Lag: 0 seconds (computed 1 second ago)
Average Apply Rate: 11.00 KByte/s
Real Time Query: OFF
Instance(s):
ORCL
Database Status:
SUCCESS
DGMGRL> edit database orcl_d set state=apply-off;
Succeeded.
DGMGRL> show database orcl_d
Database - orcl_d
Role: PHYSICAL STANDBY
Intended State: APPLY-OFF
Transport Lag: 0 seconds (computed 1 second ago)
Apply Lag: 42 seconds (computed 1 second ago)
Average Apply Rate: (unknown)
Real Time Query: OFF
Instance(s):
ORCL
Database Status:
SUCCESS
DGMGRL>
**CDB**DGMGRL> show configurationDGMGRL> show configuration
Configuration - rds_dg
Protection Mode: MaxAvailability
Members:
rdscdb_a - Primary database
rdscdb_b - Physical standby database
Fast-Start Failover: Disabled
Configuration Status:
SUCCESS (status updated 57 seconds ago)
DGMGRL> show database rdscdb_b;
Database - rdscdb_b
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 1 second ago)
Apply Lag: 0 seconds (computed 1 second ago)
Average Apply Rate: 2.00 KByte/s
Real Time Query: OFF
Instance(s):
RDSCDB
Database Status:
SUCCESS
DGMGRL> edit database rdscdb_b set state=apply-off;
Succeeded.
DGMGRL> show database rdscdb_b;
Database - rdscdb_b
Role: PHYSICAL STANDBY
Intended State: APPLY-OFF
Transport Lag: 0 seconds (computed 1 second ago)
Apply Lag: 0 seconds (computed 1 second ago)
Average Apply Rate: (unknown)
Real Time Query: OFF
Instance(s):
RDSCDB
Database Status:
SUCCESS
| 数据库管理员 |
| 以只读模式打开只读副本实例。 | 使用 TNS 条目连接到备用数据库，然后通过从主节点或备用节点连接到备用数据库，以只读模式打开该数据库。**非 CDB**$ sqlplus RDS_DATAGUARD@RDS_CUSTOM_ORCL_D as sysdg
-bash-4.2$ sqlplus RDS_DATAGUARD@RDS_CUSTOM_ORCL_D as sysdg
SQL*Plus: Release 19.0.0.0.0 - Production on Fri Sep 30 23:00:14 2022
Version 19.10.0.0.0
Copyright (c) 1982, 2020, Oracle. All rights reserved.
Enter password:
Last Successful login time: Fri Sep 30 2022 22:48:27 +00:00
Connected to:
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.10.0.0.0
SQL> select open_mode from v$database;
OPEN_MODE
--------------------
MOUNTED
SQL> alter database open read only;
Database altered.
SQL> select open_mode from v$database;
OPEN_MODE
--------------------
READ ONLY
SQL>
**CDB**-bash-4.2$ sqlplus C##RDS_DATAGUARD@RDS_CUSTOM_RDSCDB_B as sysdg
SQL*Plus: Release 19.0.0.0.0 - Production on Wed Jan 11 21:14:07 2023
Version 19.16.0.0.0
Copyright (c) 1982, 2022, Oracle. All rights reserved.
Enter password:
Last Successful login time: Wed Jan 11 2023 21:12:05 +00:00
Connected to:
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.16.0.0.0
SQL> select name,open_mode from v$database;
NAME OPEN_MODE
--------- --------------------
RDSCDB MOUNTED
SQL> alter database open read only;
Database altered.
SQL> select name,open_mode from v$database;
NAME OPEN_MODE
--------- --------------------
RDSCDB READ ONLY
SQL>
| 数据库管理员 |
| 在只读副本实例上激活重做应用。 | 在主节点或备用节点上使用 `DGMGR` L 在只读副本实例上激活重做应用。**非 CDB**$ dgmgrl RDS_DATAGUARD@RDS_CUSTOM_ORCL_D
DGMGRL for Linux: Release 19.0.0.0.0 - Production on Fri Sep 30 23:02:16 2022
Version 19.10.0.0.0
Copyright (c) 1982, 2019, Oracle and/or its affiliates. All rights reserved.
Welcome to DGMGRL, type "help" for information.
Password:
Connected to "ORCL_D"
Connected as SYSDG.
DGMGRL>
edit database orcl_d set state=apply-on;
DGMGRL> edit database orcl_d set state=apply-on;
Succeeded.
DGMGRL> show database orcl_d
Database - orcl_d
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 0 seconds ago)
Apply Lag: 0 seconds (computed 0 seconds ago)
Average Apply Rate: 496.00 KByte/s
Real Time Query: ON
Instance(s):
ORCL
Database Status:
SUCCESS
DGMGRL>
**CDB**-bash-4.2$ dgmgrl C##RDS_DATAGUARD@RDS_CUSTOM_RDSCDB_B-bash-4.2$ dgmgrl C##RDS_DATAGUARD@RDS_CUSTOM_RDSCDB_B
DGMGRL for Linux: Release 19.0.0.0.0 - Production on Wed Jan 11 21:21:11 2023
Version 19.16.0.0.0
Copyright (c) 1982, 2019, Oracle and/or its affiliates. All rights reserved.
Welcome to DGMGRL, type "help" for information.
Password:
Connected to "RDSCDB_B"
Connected as SYSDG.
DGMGRL> edit database rdscdb_b set state=apply-on;
Succeeded.
DGMGRL> show database rdscdb_b
Database - rdscdb_b
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 0 seconds ago)
Apply Lag: 0 seconds (computed 0 seconds ago)
Average Apply Rate: 35.00 KByte/s
Real Time Query: ON
Instance(s):
RDSCDB
Database Status:
SUCCESS
DGMGRL> show database rdscdb_b
Database - rdscdb_b
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 1 second ago)
Apply Lag: 0 seconds (computed 1 second ago)
Average Apply Rate: 16.00 KByte/s
Real Time Query: ON
Instance(s):
RDSCDB
Database Status:
SUCCESS
DGMGRL>
| 数据库管理员 |
## 相关的资源
+ [将 Amazon RDS 配置为 Oracle PeopleSoft 数据库](https://d1.awsstatic.com/whitepapers/configuring-amazon-rds-as-peoplesoft-database.pdf)（AWS 白皮书）
+ [Oracle Data Guard 代理指南](https://docs.oracle.com/en/database/oracle/oracle-database/19/dgbkr/index.html)（Oracle 参考文档）
+ [Data Guard 概念和管理](https://docs.oracle.com/en/database/oracle/oracle-database/19/sbydb/index.html)（Oracle 参考文档）
## 附加信息
**选择数据库保护模式**
Oracle Data Guard 提供三种保护模式，可根据您的可用性、保护和性能要求配置 Data Guard 环境。下表对这三种模式进行了汇总。
|
|
| 保护模式 | 重做传输设置 | 说明 |
| --- |--- |--- |
| ***最佳性能*** | `ASYNC` | 对于主数据库上发生的事务，重做数据将异步传输并写入备用数据库重做日志。因此，对性能的影响微乎其微。由于异步日志传送，`MaxPerformance` 无法提供 RPO=0。 |
| ***最大程度的保护*** | `SYNC+AFFIRM` | 对于主数据库上的事务，在确认事务之前，重做数据将同步传输并写入磁盘上的备用数据库重做日志。如果备用数据库不可用，则主数据库将自行关闭，以确保事务受到保护。 |
| ***最大可用性*** | `SYNC+AFFIRM` | 这类似于 `MaxProtection` 模式，除非未从备用数据库收到确认。在这种情况下，它会像在 `MaxPerformance` 模式下一样运行，以保持主数据库的可用性，直到它能够再次将其重做流写入同步备用数据库。 |
| `SYNC+NOAFFIRM` | 对于主数据库上的事务，重做将同步传输到备用数据库，并且主数据库仅等待确认已在备用数据库上收到重做，而不是等待重做已写入备用磁盘。此模式（也称为 `FastSync`）可以提供性能优势，但代价是在多个同时发生故障的特殊情况下可能会丢失数据。 |
RDS Custom for Oracle 中的只读副本是使用最高性能保护模式创建的，这也是 Oracle Data Guard 的默认保护模式。最高性能模式对主数据库的性能影响最小，这可以帮助您满足以秒为单位的恢复点目标（RPO）要求。
要努力实现零数据丢失（RPO=0）目标，可以将 Oracle Data Guard 保护模式自定义为 `MaxAvailability`，并将 `SYNC+NOAFFIRM` 作为重做传输的设置，以获得更好的性能。由于只有在将相应的重做向量成功传输到备用数据库后，才会确认主数据库上的提交，因此主实例和副本之间的网络延迟对于提交敏感型工作负载至关重要。建议对工作负载执行负载测试，以评测将只读副本自定义为在 `MaxAvailability` 模式下运行时对性能的影响。
与在不同的可用区中部署只读副本相比，将只读副本部署在与主数据库相同的可用区中可提供更低的网络延迟。但是，在同一可用区中部署主副本和只读副本可能无法满足您的 HA 要求，因为在极少数情况下，如果可用区不可用，主实例和只读副本实例都会受到影响。