Data Guard Broker中改属性是否需要两侧分别执行？
Data Guard Broker有一些属性，可以通过 show configuration 看到。
我有时会想，这些个属性，是否是分别属于primary 和 standby，如果
想要修改，是否需要分别登陆到primary 和 standby ，来分别修改呢？
这也是很多客户经常有的疑问。故此我进行了如下的实验。
先看看primary 端的 属性值：
-bash-4.1$ dgmgrl /
DGMGRL for Linux: Version 12.1.0.2.0 - 64bit Production
Copyright (c) 2000, 2013, Oracle. All rights reserved.
Welcome to DGMGRL, type "help" for information.
Connected as SYSDG.
DGMGRL> show configuration verbose;
Configuration - DRSolution
Protection Mode: MaxPerformance
Members:
orcl12102 - Primary database
orcl12102_stby - Physical standby database
Properties:
FastStartFailoverThreshold = '30'
OperationTimeout = '30'
TraceLevel = 'USER'
FastStartFailoverLagLimit = '30'
CommunicationTimeout = '180'
ObserverReconnect = '0'
FastStartFailoverAutoReinstate = 'TRUE'
FastStartFailoverPmyShutdown = 'TRUE'
BystandersFollowRoleChange = 'ALL'
ObserverOverride = 'FALSE'
ExternalDestination1 = ''
ExternalDestination2 = ''
PrimaryLostWriteAction = 'CONTINUE'
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
DGMGRL>
再看Standby 端的属性：
-bash-4.1$ dgmgrl /
DGMGRL for Linux: Version 12.1.0.2.0 - 64bit Production
Copyright (c) 2000, 2013, Oracle. All rights reserved.
Welcome to DGMGRL, type "help" for information.
Connected as SYSDG.
DGMGRL> show configuration verbose;
Configuration - DRSolution
Protection Mode: MaxPerformance
Members:
orcl12102 - Primary database
orcl12102_stby - Physical standby database
Properties:
FastStartFailoverThreshold = '30'
OperationTimeout = '30'
TraceLevel = 'USER'
FastStartFailoverLagLimit = '30'
CommunicationTimeout = '180'
ObserverReconnect = '0'
FastStartFailoverAutoReinstate = 'TRUE'
FastStartFailoverPmyShutdown = 'TRUE'
BystandersFollowRoleChange = 'ALL'
ObserverOverride = 'FALSE'
ExternalDestination1 = ''
ExternalDestination2 = ''
PrimaryLostWriteAction = 'CONTINUE'
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
DGMGRL>
从 primary 和 standby 两边看到的属性值都是一样的。所以我有一个猜测，这些属性值是共通的。
下面通过修改 CommunicationTimeout 的值来进行验证：
在primary 端修改：
DGMGRL> EDIT CONFIGURATION SET PROPERTY CommunicationTimeout=120;
Property "communicationtimeout" updated
改完后验证一下：
DGMGRL> show configuration verbose;
Configuration - DRSolution
Protection Mode: MaxPerformance
Members:
orcl12102 - Primary database
orcl12102_stby - Physical standby database
Properties:
FastStartFailoverThreshold = '30'
OperationTimeout = '30'
TraceLevel = 'USER'
FastStartFailoverLagLimit = '30'
CommunicationTimeout = '120' ******
ObserverReconnect = '0'
FastStartFailoverAutoReinstate = 'TRUE'
FastStartFailoverPmyShutdown = 'TRUE'
BystandersFollowRoleChange = 'ALL'
ObserverOverride = 'FALSE'
ExternalDestination1 = ''
ExternalDestination2 = ''
PrimaryLostWriteAction = 'CONTINUE'
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
DGMGRL>
那么，在 standby 端，会看到怎样的结果呢？
DGMGRL> show configuration verbose;
Configuration - DRSolution
Protection Mode: MaxPerformance
Members:
orcl12102 - Primary database
orcl12102_stby - Physical standby database
Properties:
FastStartFailoverThreshold = '30'
OperationTimeout = '30'
TraceLevel = 'USER'
FastStartFailoverLagLimit = '30'
CommunicationTimeout = '120' <<<<<<<<<<<<< 从 standby 端，也可以看到这个值，确实被改变了。
ObserverReconnect = '0'
FastStartFailoverAutoReinstate = 'TRUE'
FastStartFailoverPmyShutdown = 'TRUE'
BystandersFollowRoleChange = 'ALL'
ObserverOverride = 'FALSE'
ExternalDestination1 = ''
ExternalDestination2 = ''
PrimaryLostWriteAction = 'CONTINUE'
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
DGMGRL>
事实上，从 standby 端来更改其他的属性值，也是可以的，我们也可以从primary 端，连接到 data guard broker，看到同样的改变。
所以说，Data Guard Broker 搭建完毕后，如果想更改其属性值，无论是从primary 端，还是从standby 端，登陆连接到broker 后，
在哪一端修改都是可以的。