Re: More on tns configurations in the context of Dataguard
- From: kathryn axelrod <kat.axe@xxxxxxxxx>
- To: sacrophyte@xxxxxxxxx
- Date: Fri, 2 Apr 2010 10:11:15 -0700
Hi Charles,
You only need one service name in the trigger - that is the name of the
primary.
Thus if you have 10 databases (one primary, nine standbys), there would be:
db1 - service_names=prim,db1
db2 - service_names=db2
db3 - service_names=db3
and so on.
If you did a switchover from db1 to db2, it would look like:
db1 - service_names=db1
db2 - service_names=prim,db2
db3 - service_names=db3
...
In the above situation, you did the switchover and on db1, the trigger said
- am i primary? No. Stop the 'prim' service. And on db2 it said - am I
primary? Yes. Start the 'prim' service.* --Note it only stops/starts the
'prim' service with this trigger. Thus if your question was literally 'what
if I have ten service names?' - then it will simply append those ten with
the additional service name. (Or stop the additional service and leave the
other ten running).*..
The listeners have a static entry for db1, db2, db3, etc but a dynamic one
for 'prim'. Thus when db1 is no longer 'prim', its listener no longer
accepts connections for that name. Meanwhile, db2 becomes prim and its
listener starts accepting connections.
Hope this helps,
-k
On Fri, Apr 2, 2010 at 9:18 AM, Charles Schultz <sacrophyte@xxxxxxxxx>wrote:
> Good day, list,
>
> This references some past email exchanges:
>
> - Carel-Jan Engel: Data Guard (
> //www.freelists.org/post/oracle-l/Data-Guard,2)
> - Jeremy Schneider: TAF and node failover non RAC oracle 10.2 (
>
> //www.freelists.org/post/oracle-l/TAF-and-node-failover-non-RAC-oracle-102,18
> )
> - Me: Trying to wrap my head around TAF (
> //www.freelists.org/post/oracle-l/Trying-to-wrap-my-head-around-TAF,4
> )
>
>
>
> Also in reference to:
>
> - How to configure Client Failover after Data Guard Switchover or
> Failover (Doc ID 316740.1)
> - Failover Connections for Data Guard Error with ORA-1033 (Doc ID
> 461874.1)
>
>
> If I read this all correctly, the favored method to have a single tns
> connection string point to "both" (assuming two) databases in a DG
> configuration, you need:
>
> - the tns string with multiple addresses
> - properly defined service names
> - a trigger that turns the service off in the standby database
>
>
>
> So this brings up a question. Let's say, for example, you have 10 services.
> That means you have to hardcode each of those services in the manage_OCI
> trigger (from Doc ID 461874.1)? And if you insert/update/delete any of those
> service names, you have to make appropriate changes to the trigger? Is that
> not kind of a pain?
>
> Here is where I am going with this. Does not Oracle provide a way to
> disable *all* services that are registered to the listener when the
> database is started as a standby? One could add a simple loop in the
> documented manage_OCI trigger to stop each entry in SERVICE_NAMES, but that
> seems like a hack. But maybe it is the only hack available to us at this
> point in time? The Oracle online documentation does not spell out any
> options for ALL services (too bad DBMS_SERVICE.STOP_SERVICE.SERVICE_NAME
> cannot
> be null *grin*). I realize you could do some magic with local_listener, but
> that seems to overly complicate matters, IMO.
>
>
>
> --
> Charles Schultz
>
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