Database Reference
In-Depth Information
CDBFSDCA - (*) Physical standby database
Warning: ORA-16819: fast-start failover observer not started
Fast-Start Failover: ENABLED
Configuration Status:
WARNING
DGMGRL>
The little asterisk next to CDBFSDCB indicates that that standby database is the preferred failover target.
trOUBLeShOOtING USING the BrOKer LOGFILe
It is possible that the enable fast_start failover command fails. If it fails it is not immediately obvious why it
does. the Broker commands “show configuration” and “show database” do not reveal the cause of the failure.
In such cases you need to check the Broker log. the log file used by the Broker resides in the trace directory
just like the text representation of the database's alert.log. If you are unsure where to find the directory on
disk, simply query the database:
SQL> select value from v$diag_info
2 where name = 'Diag Trace';
the Broker logfile is named drc${OraCle_SID}.log. If you tail it just before you try to enable FSFO you hopefully
get meaningful errors, like this one:
09/16/2013 15:25:14
ORA-16693, FSFO requires the target standby to be in flashback mode
the error message indicated the requirement for the database to have Flashback Database enabled.
In the next step you need to start the observer on the third site. The observer is simply an instance of the
dgmgrl
utility constantly checking the standby and primary database. As such it is sufficient to install the Oracle client for
administrators or alternatively make use of an existing Broker in an RDBMS server installation. Note that the prompt
will
not
return after you started the observer, making it advisable to start the broker in its own
screen
session. Screen
is a little command line utility that should be installed by default on all machines in the author's opinion. Similar
to VNC in principle it allows you to connect to a server and keep your session on the server. The connection is
established using SSH however. Screen allows you to execute commands “in the background” using virtual sessions.
The biggest benefit is that a loss of network connectivity does not impact your work. When reconnecting to the server
you can re-attach to your screen session and resume where you left. When starting using “screen -L” it records all the
output in a log file in the current directory. When you have started the observer as shown below you can detach from
the screen session leaving the process to run. Refer to the manual page of screen for more information on how to use
screen effectively.
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