Database Reference
In-Depth Information
If the database cannot be reinstated, you will see the following message instead:
CDBFSDCA - Physical standby database (disabled)
ORA-16795: the standby database needs to be
re-created
If you had flashback database enabled and the required flashback and archived redo logs are present you can try
to reinstate the database as shown here. The database can obviously be reinstated only if it can be brought online into
the mount state, either manually or via the broker.
DGMGRL> reinstate database "CDBFSDCA"
Reinstating database "CDBFSDCA", please wait...
Reinstatement of database "CDBFSDCA" succeeded
Success! The database is now a fully functional member of the Broker configuration again:
DGMGRL> show configuration
Configuration - fsconfig
Protection Mode: MaxAvailability
Databases:
CDBFSDCB - Primary database
CDBFSDCA - Physical standby database
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
The start of redo shipping after reinstating the failed database the
protection_mode
and
protection_level
columns in
v$database
will be both set to “MAXIMUM AVAILABILITY”. You can begin raising a change request
to reverse the roles during the next change window. Before doing so you should ensure that the broker does not
complain; missing standby redo logs are a common cause for a warning. Block Change Tracking might need to be
enabled, and Oracle Clusterware metadata for the databases should be reviewed and amended where needed.
Creating a lights-out configuration using the Broker
The Data Guard Broker can also be configured for a lights-out situation. Lights-out can be understood as an
environment where the management of failover operations is delegated to software. In the case of Data Guard this
software is called the Observer. The observer process, which should ideally be in a third site, has the task to monitor
the primary database. Under certain conditions the failover operation can be initiated by the Observer, without
human intervention at all. Refer back to Figure
10-1
for a description of the architecture. The Observer in this case is
located in data center C, and the database configuration consists of the primary database in data center A and a single
standby database in data center B. For this Broker configuration there is no third database, although it is possible to
have many standby databases, even a mix of physical and logical.
The Fast Start Failover or FSFO configuration is always based on an existing Broker configuration such as the one
shown here:
DGMGRL> show configuration verbose
Configuration - fsconfig
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