In an Oracle Dataguard environment with Fast-Start Failover activated, you should be able to automate the restart of an “Observer”. This exactly what the script performs.
First of all you need to prepare the environment.
Add the ORACLE_SID into the ORATAB
Create under ${DMK_ORA_ADMIN_SID} a “etc” directory
Source DMK to load the new configuration
Copy into “${DMK_ORA_ADMIN_SID}/etc” the dgobserver.cfg template
cat ${DMK_HOME}/templates/etc/dgobserver.cfg
# template dgcheck.cfg - defines variables for the observer monitoring script
#****************************************************************************************
# Connection string to the ConfigurationWideServiceName
# create an entry in tnsnames.ora with
# <DB_NAME>_CFG.<DB_DOMAIN>=
# (DESCRIPTION =(ADDRESS=(PROTOCOL=TCP)(HOST=<host1>)(PORT=1521))(ADDRESS=(PROTOCOL=TCP)(HOST=<host2>)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=<db_name>_CFG.<DB_DOMAIN>)))
ConnectStringConfigWide="/@<DB_UNIQUE_NAME>.<DB_DOMAIN>"
# To use 'in background' start-option, a wallet-connect (/@alias) is required
#****************************************************************************************
# Connection string to the primary - only to specify if not using ConnectStringConfigWide
#ConnectStringPrim="sys/xxxx@<DB_UNIQUE_NAME>.<DB_DOMAIN>"
#****************************************************************************************
# Connection string to the Standby - only to specify if not using ConnectStringConfigWide
#ConnectStringStdb="sys/xxxx@<DB_UNIQUE_NAME>.<DB_DOMAIN>"
#****************************************************************************************
# Kill the Observer process once timeout has been reached (seconds)
ObserverStopHardlyTimeOut=30
#****************************************************************************************
# This parameter specify how long the script retries to reach
# the databases in order to start the observer (seconds)
ObserverRebootRetryTime=600
It is recommended to connect to the configuration wide service name
DGMGRL> show configuration ConfigurationWideServiceName
This service is registered by all running database sites with the local listener. It is recommended to create a tnsnames alias <DB_UNIQUE_NAME>.<DB_DOMAIN> using this service (per default <db_name>_CFG.<db_domain>).
As highlighted by the above configuration the script tries to reach at least one database instance (regardless of the database role) in order to start/stop the observer and enter in a loop which retries to connect to the database for about 10minutes.
This is especially useful in case of a reboot; mostly the database servers needs more time to complete the boot sequence. Therefore the script loops for 10min before it gives-up.
Syntax
dgobserver.ksh [start|stop|status] [SID]
Do not forget to add the script into the “${DMK_HOME}/etc/service_start_stop.cfg” configuration file in order to start/ the observer in case of a reboot.
