Observer is Dbvisit StandbyMP component which is embedded in dbvcontrol and is operatated automatically by starting or stopping dbvctonrol. Purpose of observer is to periodically check primary and standby database, primary and standby server, send notifications and / or initiate Automatic failover.

1. Observer Concept

Observer performs check whether host is alive by checking the dbvagentmanager. If the dbvagentmanager is unreachable, the host is then reported as down by observer. Observer checks the database status through dbvagentmanager.

Open

Observer concept is the same and does same checks for all three database platforms: Oracle, Postrges and SQL Server.

Observer send notifications every time server or database become unreachable. The reported error is however always the same “Primary/Standby database check failed” regardless whether whole server or only database fail the status check.

User can customize interval between checks and number of failed checks. The number of failed checks have following purpose:

• If number of failed checks is exceeded for primary or standby database/server and Observer is set to “Notifications Only”, observer disables any further notifications, but remains checking silently in the background

• If number of failed checks is exceeded for primary database/server and Observer is set to “Perform Automatic Failover”, observer activates standby database, and disables itself for particular configuration

• If number of failed checks is exceeded for standby database/server and Observer is set to “Perform Automatic Failover”, the situation is treated as if Observer is set to “Notifications Only”

2. Observer Configuration

Observer is always enabled separately for each DDC configuration. To configrue the observer, you need to click on “Observer/Auto Failover” in the right ACTIONS pane:

Open

You will then see following Observer Configuration options:

Open

Explanation of individual options:

Number	Description	Setting Explanation

Number	Description	Setting Explanation
1	Enable/Disable Observer	Wholly enables or disables observer for particular DDC. Observer gets automatically disabled in certain processes. For example disabled at start of graceful switchover and enabled again once the switchover is completed.
2	Selected Emergency Action	Preffered emergency action which will take place once number of failed checks is reached. Notifications Only = observer sends only notifications. If number of failed checks is reached, notifications will be disabled Perform Automatic Failover = If number of failed checks is reached, observer activates standby database, and disables itself for particular configuration
3	Number of failed checks and interval	You can specify number of failed checks and intervals between the checks. When using automatic failover, It is helpful to consider common situations such as scheduled server reboots and set the intervals + the number of check so as there would not be accidental standby database activation during such scheduled reboot.
4	Type of notifications to send	You can choose between Email and Slack notifications. Observer will then send notifications via chosen channel. If no mail nor slack notifications are enabled, observer will notify user through events visible in the dashboard task pane.
5	Heartbeat Message	This option is only valid if either Email or Slack notifications are selected. At specified time, notification is sent about status of dbvisit sychronization. Heartbeat notification contains following text: Heartbeat for <DDC> The Dbvisit Observer is monitoring configuration <DDC>. The primary database on <primary host> is ONLINE. The standby database on <standby host> is RECOVERING.. Automated Standby Update is not enabled. The current Time Gap is 2 minutes 38 seconds. Specified in 24hr format, for example: Open
6	Custom Observer Scripts	Described in detail further on this page. User has possibility of replacing default observer check scripts with custom checks
7	Save or discard changes