{"id":17175,"date":"2022-04-15T12:33:52","date_gmt":"2022-04-15T10:33:52","guid":{"rendered":"https:\/\/www.dbi-services.com\/blog\/oracle-data-guard-where-to-host-the-master-observer\/"},"modified":"2023-06-20T10:15:16","modified_gmt":"2023-06-20T08:15:16","slug":"oracle-data-guard-where-to-host-the-master-observer","status":"publish","type":"post","link":"https:\/\/www.dbi-services.com\/blog\/oracle-data-guard-where-to-host-the-master-observer\/","title":{"rendered":"Oracle Data Guard : Where to Host The Master Observer"},"content":{"rendered":"

By Mouhamadou Diaw<\/strong><\/p>\n

An observer is an OCI client that connects to the primary and target standby databases using the same SYS credentials you used when you connected to the Oracle Data Guard configuration with DGMGRL.
\nThe observer is highly recommended in a Data Guard environment. But it is mandatory if a Fast-Start Failover is configured.<\/p>\n

Since Oracle 12.2 we can have up to 3 observers and the maximum number of observers is increased to 4 since Oracle 21c. One important thing is that even if we have multiple observers, only one observer is the master and all other are backup observers. Only the master observer can initiate a fast-start failover process.<\/p>\n

The question we often ask is where to host my observers. Does the support of multiple observers close this question?
\nIn this blog I am trying to test many scenarios so that we will have an idea of where to put my observers.<\/p>\n

I will suppose that I have 3 datacenters
\n-The primary datacenter hosting the primary server oraadserver<\/strong>
\n-The secondary datacenter hosting the primary server oraadserver1<\/strong>
\n-The third datacenter where I have the server oraadserver3<\/strong> I can use for observer for example<\/p>\n

The fast-start failover is already configured, and I have 3 observers<\/p>\n

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\n
\n
DGMGRL> show configuration verbose<\/code><\/div>\n
<\/div>\n
Configuration - db21<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Protection Mode: MaxPerformance<\/code><\/div>\n
\u00a0\u00a0<\/code>Members:<\/code><\/div>\n
\u00a0\u00a0<\/code>DB21_SITE1 - <\/code>Primary<\/code> database<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DB21_SITE2 - (*) Physical standby <\/code>database<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>(*) Fast-Start Failover target<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Properties:<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>FastStartFailoverThreshold\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'15'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>OperationTimeout\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'30'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>TraceLevel\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'USER'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>FastStartFailoverLagLimit\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'30'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>CommunicationTimeout\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'180'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ObserverReconnect\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'0'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ObserverPingInterval\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'0'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ObserverPingRetry\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'0'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>FastStartFailoverAutoReinstate\u00a0 = <\/code>'TRUE'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>FastStartFailoverPmyShutdown\u00a0\u00a0\u00a0 = <\/code>'TRUE'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>BystandersFollowRoleChange\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'ALL'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ObserverOverride\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'FALSE'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ExternalDestination1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>''<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ExternalDestination2\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>''<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>PrimaryLostWriteAction\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'CONTINUE'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ConfigurationWideServiceName\u00a0\u00a0\u00a0 = <\/code>'DB21_CFG'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>ConfigurationSimpleName\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'db21'<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DrainTimeout\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = <\/code>'0'<\/code><\/div>\n
<\/div>\n
Fast-Start Failover: Enabled <\/code>in<\/code> Potential Data Loss Mode<\/code><\/div>\n
\u00a0\u00a0<\/code>Lag Limit:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 30 seconds<\/code><\/div>\n
\u00a0\u00a0<\/code>Threshold:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 15 seconds<\/code><\/div>\n
\u00a0\u00a0<\/code>Ping Interval:\u00a0\u00a0\u00a0\u00a0\u00a0 3000 milliseconds<\/code><\/div>\n
\u00a0\u00a0<\/code>Ping Retry:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0<\/code><\/div>\n
\u00a0\u00a0<\/code>Active Target:\u00a0\u00a0\u00a0\u00a0\u00a0 DB21_SITE2<\/code><\/div>\n
\u00a0\u00a0<\/code>Potential Targets:\u00a0 <\/code>\"DB21_SITE2\"<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DB21_SITE2 valid<\/code><\/div>\n
\u00a0\u00a0<\/code>Observers:\u00a0\u00a0\u00a0\u00a0\u00a0 (*) oraadserver1<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>oraadserver21<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>oraadserver31<\/code><\/div>\n
\u00a0\u00a0<\/code>Shutdown <\/code>Primary<\/code>:\u00a0\u00a0 <\/code>TRUE<\/code><\/div>\n
\u00a0\u00a0<\/code>Auto-reinstate:\u00a0\u00a0\u00a0\u00a0 <\/code>TRUE<\/code><\/div>\n
\u00a0\u00a0<\/code>Observer Reconnect: (none)<\/code><\/div>\n
\u00a0\u00a0<\/code>Observer Override:\u00a0 <\/code>FALSE<\/code><\/div>\n
<\/div>\n
Configuration Status:<\/code><\/div>\n
SUCCESS<\/code><\/div>\n
<\/div>\n
DGMGRL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

Case 1 : The master observer is running on oraadserver so the observer is located in the primary datacenter <\/strong><\/p>\n

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\n
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DGMGRL> show observer<\/code><\/div>\n
<\/div>\n
Configuration - db21<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Fast-Start Failover:\u00a0\u00a0\u00a0\u00a0 ENABLED<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 DB21_SITE1<\/code><\/div>\n
\u00a0\u00a0<\/code>Active Target:\u00a0\u00a0\u00a0\u00a0\u00a0 DB21_SITE2<\/code><\/div>\n
<\/div>\n
Observer <\/code>\"oraadserver1\"<\/code> - Master<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Host <\/code>Name<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 oraadserver<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Target:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Log File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/log\/observer_oraadserver.log<\/code><\/div>\n
\u00a0\u00a0<\/code>State File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/dat\/fsfo.dat<\/code><\/div>\n
<\/div>\n
Observer <\/code>\"oraadserver21\"<\/code> - Backup<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Host <\/code>Name<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 oraadserver2<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Target:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Log File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/log\/observer_oraadserver2.log<\/code><\/div>\n
\u00a0\u00a0<\/code>State File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/dat\/fsfo.dat<\/code><\/div>\n
<\/div>\n
Observer <\/code>\"oraadserver31\"<\/code> - Backup<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Host <\/code>Name<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 oraadserver3<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Target:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Log File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/log\/observer_oraadserver3.log<\/code><\/div>\n
\u00a0\u00a0<\/code>State File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/dat\/fsfo.dat<\/code><\/div>\n
<\/div>\n
DGMGRL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

The first test I am doing is to simulate the loss of the first datacenter and to see if a fast-start failover will happen. The loss of the primary datacenter means that I lose both primary database and master observer<\/p>\n

Ok let’s poweroff the primary server<\/p>\n

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[root@oraadserver ~]<\/code># poweroff<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

In the logfile of one observer located in a remaining datacenter (oraadserver3) we can see following lines<\/p>\n

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[W000 2022-04-15T12:48:16.563+02:00] Primary database cannot be reached.<\/code><\/div>\n
[W000 2022-04-15T12:48:16.563+02:00] Fast-Start Failover threshold has not exceeded. Retry <\/code>for<\/code> the next 2 seconds<\/code><\/div>\n
[W000 2022-04-15T12:48:17.563+02:00] Try to connect to the primary.<\/code><\/div>\n
[W000 2022-04-15T12:48:19.891+02:00] Primary database cannot be reached.<\/code><\/div>\n
[W000 2022-04-15T12:48:19.891+02:00] Fast-Start Failover threshold has expired.<\/code><\/div>\n
[W000 2022-04-15T12:48:19.891+02:00] Try to connect to the standby.<\/code><\/div>\n
[W000 2022-04-15T12:48:19.891+02:00] Check <\/code>if<\/code> the standby is ready <\/code>for<\/code> failover.<\/code><\/div>\n
[W000 2022-04-15T12:48:19.899+02:00] Fast-Start Failover is not possible because this observer is not the master.<\/code><\/div>\n
[W000 2022-04-15T12:48:20.902+02:00] Try to connect to the primary.<\/code><\/div>\n
[W000 2022-04-15T12:48:28.908+02:00] Primary database cannot be reached.<\/code><\/div>\n
[W000 2022-04-15T12:48:28.908+02:00] Fast-Start Failover threshold has not exceeded. Retry <\/code>for<\/code> the next 7 seconds<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

As expected, the fast_start failover did not happen because the master observer was down. But the question is why another observer was not promoted as a master. Yes I have 3 observers, I am expecting that when the master crash that a backup observer will become the master.<\/p>\n

I then restart the primary server and confirm that the db_site1 is still the primary database<\/p>\n

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\n
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DGMGRL> show configuration<\/code><\/div>\n
<\/div>\n
Configuration - db21<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Protection Mode: MaxPerformance<\/code><\/div>\n
\u00a0\u00a0<\/code>Members:<\/code><\/div>\n
\u00a0\u00a0<\/code>DB21_SITE1 - <\/code>Primary<\/code> database<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DB21_SITE2 - (*) Physical standby <\/code>database<\/code><\/div>\n
<\/div>\n
Fast-Start Failover: Enabled <\/code>in<\/code> Potential Data Loss Mode<\/code><\/div>\n
<\/div>\n
Configuration Status:<\/code><\/div>\n
SUCCESS\u00a0\u00a0 (status updated 31 seconds ago)<\/code><\/div>\n
<\/div>\n
DGMGRL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

Ok, we restart everything and still have the master observer in the primary datacenter<\/p>\n

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\n
\n
DGMGRL> show fast_start failover<\/code><\/div>\n
<\/div>\n
Fast-Start Failover: Enabled <\/code>in<\/code> Potential Data Loss Mode<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Protection Mode:\u00a0\u00a0\u00a0 MaxPerformance<\/code><\/div>\n
\u00a0\u00a0<\/code>Lag Limit:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 30 seconds<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Threshold:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 15 seconds<\/code><\/div>\n
\u00a0\u00a0<\/code>Ping Interval:\u00a0\u00a0\u00a0\u00a0\u00a0 3000 milliseconds<\/code><\/div>\n
\u00a0\u00a0<\/code>Ping Retry:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0<\/code><\/div>\n
\u00a0\u00a0<\/code>Active Target:\u00a0\u00a0\u00a0\u00a0\u00a0 DB21_SITE2<\/code><\/div>\n
\u00a0\u00a0<\/code>Potential Targets:\u00a0 <\/code>\"DB21_SITE2\"<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DB21_SITE2 valid<\/code><\/div>\n
\u00a0\u00a0<\/code>Observers:\u00a0\u00a0\u00a0\u00a0\u00a0 (*) oraadserver1<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>oraadserver21<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>oraadserver31<\/code><\/div>\n
\u00a0\u00a0<\/code>Shutdown <\/code>Primary<\/code>:\u00a0\u00a0 <\/code>TRUE<\/code><\/div>\n
\u00a0\u00a0<\/code>Auto-reinstate:\u00a0\u00a0\u00a0\u00a0 <\/code>TRUE<\/code><\/div>\n
\u00a0\u00a0<\/code>Observer Reconnect: (none)<\/code><\/div>\n
\u00a0\u00a0<\/code>Observer Override:\u00a0 <\/code>FALSE<\/code><\/div>\n
<\/div>\n
Configurable Failover Conditions<\/code><\/div>\n
\u00a0\u00a0<\/code>Health Conditions:<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Corrupted Controlfile\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 YES<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Corrupted Dictionary\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 YES<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Inaccessible Logfile\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/code>NO<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Stuck Archiver\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/code>NO<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Datafile Write Errors\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 YES<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Oracle Error Conditions:<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>(none)<\/code><\/div>\n
<\/div>\n
DGMGRL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

And let’s kill the observer without crashing the datacenter (we only crash the observer not the primary database)<\/p>\n

\n
\n\n\n\n
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\n
\n
[oracle@oraadserver ~]$ <\/code>ps<\/code> -ef | <\/code>grep<\/code> -i observer<\/code><\/div>\n
oracle\u00a0\u00a0 12816\u00a0\u00a0\u00a0\u00a0 1\u00a0 0 12:55 ?\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 00:00:01 <\/code>\/u01\/app\/oracle\/product\/dbhome_1\/bin\/dgmgrl<\/code> START OBSERVER NONAME FILE IS <\/code>'fsfo.dat'<\/code><\/div>\n
oracle\u00a0\u00a0 12988 12959\u00a0 0 12:57 pts<\/code>\/2<\/code>\u00a0\u00a0\u00a0 00:00:00 <\/code>grep<\/code> --color=auto -i observer<\/code><\/div>\n
[oracle@oraadserver ~]$<\/code><\/div>\n
<\/div>\n
<\/div>\n
[oracle@oraadserver ~]$ <\/code>kill<\/code> -9 12816<\/code><\/div>\n
[oracle@oraadserver ~]$<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

We can see in this case that the observer located in another datacenter was promoted to a master one as few minutes after. A fast-start failover will happen if now we crash the primary datacenter.<\/p>\n

\n
\n\n\n\n
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\n
\n
DGMGRL> show fast_start failover<\/code><\/div>\n
<\/div>\n
Fast-Start Failover: Enabled <\/code>in<\/code> Potential Data Loss Mode<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Protection Mode:\u00a0\u00a0\u00a0 MaxPerformance<\/code><\/div>\n
\u00a0\u00a0<\/code>Lag Limit:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 30 seconds<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Threshold:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 15 seconds<\/code><\/div>\n
\u00a0\u00a0<\/code>Ping Interval:\u00a0\u00a0\u00a0\u00a0\u00a0 3000 milliseconds<\/code><\/div>\n
\u00a0\u00a0<\/code>Ping Retry:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0<\/code><\/div>\n
\u00a0\u00a0<\/code>Active Target:\u00a0\u00a0\u00a0\u00a0\u00a0 DB21_SITE2<\/code><\/div>\n
\u00a0\u00a0<\/code>Potential Targets:\u00a0 <\/code>\"DB21_SITE2\"<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DB21_SITE2 valid<\/code><\/div>\n
\u00a0\u00a0<\/code>Observers:\u00a0\u00a0\u00a0\u00a0\u00a0 (*) oraadserver21<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>oraadserver1<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>oraadserver31<\/code><\/div>\n
\u00a0\u00a0<\/code>Shutdown <\/code>Primary<\/code>:\u00a0\u00a0 <\/code>TRUE<\/code><\/div>\n
\u00a0\u00a0<\/code>Auto-reinstate:\u00a0\u00a0\u00a0\u00a0 <\/code>TRUE<\/code><\/div>\n
\u00a0\u00a0<\/code>Observer Reconnect: (none)<\/code><\/div>\n
\u00a0\u00a0<\/code>Observer Override:\u00a0 <\/code>FALSE<\/code><\/div>\n
<\/div>\n
Configurable Failover Conditions<\/code><\/div>\n
\u00a0\u00a0<\/code>Health Conditions:<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Corrupted Controlfile\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 YES<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Corrupted Dictionary\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 YES<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Inaccessible Logfile\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/code>NO<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Stuck Archiver\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/code>NO<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Datafile Write Errors\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 YES<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Oracle Error Conditions:<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>(none)<\/code><\/div>\n
<\/div>\n
DGMGRL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

So seems that if we lose at the same time the master observer and the primary database, no backup observer is promoted to a master.<\/p>\n

Case 2 : The master observer is running on oraadserver2 so the observer is located in the secondary datacenter <\/strong><\/p>\n

In this second test, the master observer is in the same datacenter that the standby database. Let’s simulate a crash of the secondary datacenter by crashing the standby server and see what happens<\/p>\n

\n
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\n
\n
DGMGRL> show fast_start failover;<\/code><\/div>\n
<\/div>\n
Fast-Start Failover: Enabled <\/code>in<\/code> Potential Data Loss Mode<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Protection Mode:\u00a0\u00a0\u00a0 MaxPerformance<\/code><\/div>\n
\u00a0\u00a0<\/code>Lag Limit:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 30 seconds<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Threshold:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 15 seconds<\/code><\/div>\n
\u00a0\u00a0<\/code>Ping Interval:\u00a0\u00a0\u00a0\u00a0\u00a0 3000 milliseconds<\/code><\/div>\n
\u00a0\u00a0<\/code>Ping Retry:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0<\/code><\/div>\n
\u00a0\u00a0<\/code>Active Target:\u00a0\u00a0\u00a0\u00a0\u00a0 DB21_SITE2<\/code><\/div>\n
\u00a0\u00a0<\/code>Potential Targets:\u00a0 <\/code>\"DB21_SITE2\"<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>DB21_SITE2 valid<\/code><\/div>\n
\u00a0\u00a0<\/code>Observers:\u00a0\u00a0\u00a0\u00a0\u00a0 (*) oraadserver21<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>oraadserver1<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code>oraadserver31<\/code><\/div>\n
\u00a0\u00a0<\/code>Shutdown <\/code>Primary<\/code>:\u00a0\u00a0 <\/code>TRUE<\/code><\/div>\n
\u00a0\u00a0<\/code>Auto-reinstate:\u00a0\u00a0\u00a0\u00a0 <\/code>TRUE<\/code><\/div>\n
\u00a0\u00a0<\/code>Observer Reconnect: (none)<\/code><\/div>\n
\u00a0\u00a0<\/code>Observer Override:\u00a0 <\/code>FALSE<\/code><\/div>\n
<\/div>\n
Configurable Failover Conditions<\/code><\/div>\n
\u00a0\u00a0<\/code>Health Conditions:<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Corrupted Controlfile\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 YES<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Corrupted Dictionary\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 YES<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Inaccessible Logfile\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/code>NO<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Stuck Archiver\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/code>NO<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>Datafile Write Errors\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 YES<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Oracle Error Conditions:<\/code><\/div>\n
\u00a0\u00a0\u00a0\u00a0<\/code>(none)<\/code><\/div>\n
<\/div>\n
DGMGRL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

Let’s poweroff the standby server<\/p>\n

\n
\n\n\n\n
\n
1<\/div>\n<\/td>\n
\n
\n
[root@oraadserver2 ~]<\/code># poweroff<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

As expected, there was not a fast-start failover as I lose both standby database and observer because no backup observer was promoted.
\nAnd what is also important is that my primary database was shut down by Oracle. Indeed if the alert log of the primary database we can see following lines<\/p>\n

\n
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\n
\n
Thread 1 advanced to log sequence 33 (LGWR switch),\u00a0 current SCN: 77729099<\/code><\/div>\n
\u00a0\u00a0<\/code>Current log<\/code># 1 seq# 33 mem# 0: \/u01\/app\/oracle\/oradata\/DB21\/onlinelog\/o1_mf_1_hx1xy9yc_.log<\/code><\/div>\n
\u00a0\u00a0<\/code>Current log<\/code># 1 seq# 33 mem# 1: \/u01\/app\/oracle\/fast_recovery_area\/DB21\/onlinelog\/o1_mf_1_hx1xybv4_.log<\/code><\/div>\n
2022-04-15T13:09:26.832279+02:00<\/code><\/div>\n
ARC0 (PID:12144): Archived Log entry 907 added <\/code>for<\/code> B-1101901028.T-1.S-32 ID 0x465cfcd1 LAD:1 [krse.c:4912]<\/code><\/div>\n
2022-04-15T13:10:01.882983+02:00<\/code><\/div>\n
Fast-Start Failover reconfiguration <\/code>in<\/code> progress.<\/code><\/div>\n
2022-04-15T13:10:04.874482+02:00<\/code><\/div>\n
DMON: FSFP network call timeout. Killing process FSFP.<\/code><\/div>\n
2022-04-15T13:10:04.898659+02:00<\/code><\/div>\n
Process termination requested <\/code>for<\/code> pid 12003 [<\/code>source<\/code> = rdbms], [info = 2] [request issued by pid: 11934, uid: 54323]<\/code><\/div>\n
2022-04-15T13:10:07.914848+02:00<\/code><\/div>\n
Starting background process FSFP<\/code><\/div>\n
2022-04-15T13:10:07.986554+02:00<\/code><\/div>\n
FSFP started with pid=7, OS <\/code>id<\/code>=13725<\/code><\/div>\n
2022-04-15T13:10:11.906564+02:00<\/code><\/div>\n
Primary has heard from neither observer nor target standby within FastStartFailoverThreshold seconds.<\/code><\/div>\n
It is likely an automatic failover has already occurred. Primary is shutting down.<\/code><\/div>\n
2022-04-15T13:10:11.911704+02:00<\/code><\/div>\n
Errors <\/code>in<\/code> file<\/code> \/u01\/app\/oracle\/diag\/rdbms\/db21_site1\/DB21\/trace\/DB21_lg00_11908<\/code>.trc:<\/code><\/div>\n
ORA-16830: primary isolated from fast-start failover partners longer than FastStartFailoverThreshold seconds: shutting down<\/code><\/div>\n
USER (ospid: 11908): terminating the instance due to ORA error 16830<\/code><\/div>\n
2022-04-15T13:10:12.031189+02:00<\/code><\/div>\n
System state dump requested by (instance=1, osid=11908 (LG00)), summary=[abnormal instance termination].<\/code><\/div>\n
2022-04-15T13:10:12.031406+02:00<\/code><\/div>\n
Memory (Avail \/ Total) = 792.82M \/ 3789.53M<\/code><\/div>\n
Swap (Avail \/ Total) = 3072.00M \/\u00a0 3072.00M<\/code><\/div>\n
<\/div>\n
2022-04-15T13:10:12.125885+02:00<\/code><\/div>\n
System State dumped to trace <\/code>file<\/code> \/u01\/app\/oracle\/diag\/rdbms\/db21_site1\/DB21\/trace\/DB21_diag_11877<\/code>.trc<\/code><\/div>\n
2022-04-15T13:10:12.699552+02:00<\/code><\/div>\n
Dumping diagnostic data <\/code>in<\/code> directory=[cdmp_20220415131012], requested by (instance=1, osid=11908 (LG00)), summary=[abnormal instance termination].<\/code><\/div>\n
2022-04-15T13:10:13.866769+02:00<\/code><\/div>\n
Instance terminated by USER, pid = 11908<\/code><\/div>\n
2022-04-15T13:12:58.049262+02:00<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

This means that if your master observer is located in the same datacenter that the standby server, if your standby datacenter crash,
\n-No automatic failover will happen
\n-Your primary database will be shutdown<\/p>\n

Case 3 : The master observer is running on oraadserver3 so the observer is located in the third datacenter <\/strong><\/p>\n

\n
\n\n\n\n
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\n
\n
DGMGRL> show observer<\/code><\/div>\n
<\/div>\n
Configuration - db21<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Fast-Start Failover:\u00a0\u00a0\u00a0\u00a0 ENABLED<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 DB21_SITE1<\/code><\/div>\n
\u00a0\u00a0<\/code>Active Target:\u00a0\u00a0\u00a0\u00a0\u00a0 DB21_SITE2<\/code><\/div>\n
<\/div>\n
Observer <\/code>\"oraadserver31\"<\/code> - Master<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Host <\/code>Name<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 oraadserver3<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 <\/code>second<\/code> ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Target:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 <\/code>second<\/code> ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Log File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/log\/observer_oraadserver3.log<\/code><\/div>\n
\u00a0\u00a0<\/code>State File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/dat\/fsfo.dat<\/code><\/div>\n
<\/div>\n
Observer <\/code>\"oraadserver1\"<\/code> - Backup<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Host <\/code>Name<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 oraadserver<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 <\/code>second<\/code> ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Target:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Log File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/log\/observer_oraadserver.log<\/code><\/div>\n
\u00a0\u00a0<\/code>State File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/dat\/fsfo.dat<\/code><\/div>\n
<\/div>\n
Observer <\/code>\"oraadserver21\"<\/code> - Backup<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Host <\/code>Name<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 oraadserver2<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 <\/code>second<\/code> ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Target:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Log File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/log\/observer_oraadserver2.log<\/code><\/div>\n
\u00a0\u00a0<\/code>State File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/dat\/fsfo.dat<\/code><\/div>\n
<\/div>\n
DGMGRL><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

Now let’s crash the third datacenter which only host the master observer, no primary or standby database is running on this datacenter.<\/p>\n

\n
\n\n\n\n
\n
1<\/div>\n<\/td>\n
\n
\n
[root@oraadserver3 ~]<\/code># poweroff<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

A few minutes after, a backup observer was automatically promoted to a master one.<\/p>\n

\n
\n\n\n\n
\n
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\n
\n
DGMGRL> show observer<\/code><\/div>\n
<\/div>\n
Configuration - db21<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Fast-Start Failover:\u00a0\u00a0\u00a0\u00a0 ENABLED<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 DB21_SITE1<\/code><\/div>\n
\u00a0\u00a0<\/code>Active Target:\u00a0\u00a0\u00a0\u00a0\u00a0 DB21_SITE2<\/code><\/div>\n
<\/div>\n
Observer <\/code>\"oraadserver1\"<\/code> - Master<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Host <\/code>Name<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 oraadserver<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Target:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Log File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/log\/observer_oraadserver.log<\/code><\/div>\n
\u00a0\u00a0<\/code>State File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/dat\/fsfo.dat<\/code><\/div>\n
<\/div>\n
Observer <\/code>\"oraadserver21\"<\/code> - Backup<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Host <\/code>Name<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 oraadserver2<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Target:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Log File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/log\/observer_oraadserver2.log<\/code><\/div>\n
\u00a0\u00a0<\/code>State File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/dat\/fsfo.dat<\/code><\/div>\n
<\/div>\n
Observer <\/code>\"oraadserver31\"<\/code> - Backup<\/code><\/div>\n
<\/div>\n
\u00a0\u00a0<\/code>Host <\/code>Name<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 oraadserver3<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Primary<\/code>:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 59 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Last<\/code> Ping <\/code>to<\/code> Target:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 59 seconds ago<\/code><\/div>\n
\u00a0\u00a0<\/code>Log File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/log\/observer_oraadserver3.log<\/code><\/div>\n
\u00a0\u00a0<\/code>State File:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/u01\/app\/oracle\/admin\/prod20\/broker_files\/config_db21\/dat\/fsfo.dat<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

To resume we can see that<\/p>\n

Prmiary database and master observer in the same datacenter
\n-loss of datacenter = No automatic failover because no master observer promoted<\/p>\n

Standby database and master observer in the same datacenter
\n-loss of datacenter = No automatic failover because no master observer promoted + shutdown of primary database<\/p>\n

Master observer in a third datacenter
\n-loss of datacenter = a backup observer will be promoted to a master one.<\/p>\n

Conclusion<\/h3>\n

I will conclude with a question
\nWhere will you put your master observer if you have
\n2 datacenters?
\n3 datacenter?<\/p>\n

Hope this blog will help<\/p>\n","protected":false},"excerpt":{"rendered":"

By Mouhamadou Diaw An observer is an OCI client that connects to the primary and target standby databases using the same SYS credentials you used when you connected to the Oracle Data Guard configuration with DGMGRL. The observer is highly recommended in a Data Guard environment. But it is mandatory if a Fast-Start Failover is […]<\/p>\n","protected":false},"author":27,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[229,198,59],"tags":[1649,2542,137,2513],"type_dbi":[],"class_list":["post-17175","post","type-post","status-publish","format-standard","hentry","category-database-administration-monitoring","category-database-management","category-oracle","tag-automatic-failover","tag-observers","tag-oracle-21c","tag-oracle-21c-borker-new-feature"],"acf":[],"yoast_head":"\nOracle Data Guard : Where to Host The Master Observer - dbi Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.dbi-services.com\/blog\/oracle-data-guard-where-to-host-the-master-observer\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Oracle Data Guard : Where to Host The Master Observer\" \/>\n<meta property=\"og:description\" content=\"By Mouhamadou Diaw An observer is an OCI client that connects to the primary and target standby databases using the same SYS credentials you used when you connected to the Oracle Data Guard configuration with DGMGRL. 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