RE: Switchover of Logical Standby database
- From: Mathias Zarick <Mathias.Zarick@xxxxxxxxxxxx>
- To: "gerry@xxxxxxxxxxxxxxxxxxx" <gerry@xxxxxxxxxxxxxxxxxxx>
- Date: Sun, 18 Dec 2011 09:28:37 +0000
Hi Gerry,
try this in your after role change trigger:
DBMS_SERVICE.STOP_SERVICE('YOUR_SERVICE');
DBMS_SERVICE.DISCONNECT_SESSION('YOUR_SERVICE',DBMS_SERVICE.IMMEDIATE);
HTH Mathias
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Gerry Miller
Sent: Saturday, December 17, 2011 12:08 AM
To: CRISLER, JON A
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: Switchover of Logical Standby database
Hi Jon
Thanks for your response.
The clients connect via tnsnames, which is set up for CTF and TAF. I
originally created a physical configuration, which I tested for TAF and when a
switchover was performed it worked as I expected: a session that was running a
query on the original primary ran to completion on the new primary. I then
converted the physical standby to a logical standby, dropping and recreating
the data guard broker configuration accordingly and switchover and failover
worked.
In the physical configuration I had TAF configured via tnsnames:
ORCL =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP) (HOST = server1) (PORT = 1521) )
(ADDRESS = (PROTOCOL = TCP) (HOST = server2) (PORT = 1521) )
(CONNECT_DATA = (SERVICE_NAME=ORCL_PRIMARY)
(FAILOVER_MODE= (TYPE=SELECT) (RETRIES=1000) (DELAY=60)
(METHOD=BASIC) ) ) )
and started the ORCL_PRIMARY service via a database startup trigger. In the
logical configuration I added a trigger to stop and start the service on
db_role_change. Both of these triggers function as expected.
The fact that the databases are not restarted on a logical standby
switchovermakes me wonder when TAF is supposed to occur. At no time does the
client session lose connection, which is the point at which it would be
redirected to the primary database service via tnsnames. Even in the case ofa
logical standby failover the original primary database is still up and running
(albeit as a disabled standby) and connections persist. It seems to me that a
restart of at least the logical standby is required to cause TAF.
This behaviour occurs not only via the application but also from a sqlplus
session on the database server, so it is not a client configuration issue.
Active Dataguard is not an option as we are on 10g.
Regards
Gerry
CRISLER, JON A wrote: Are your clients configured with connect strings (jdbc or
tnsnames) where both primary and standby sides are defied? Also is your app TAF
compliant? And are you using Active Dataguard ? I suspect more a client
configuration issue. I have seen funny behavior like this when older clients
are connecting to new databases, or bugs in the client side. This is why one
should make sure that the client is upgraded to the same level as thedb. We
have numerous configurations on 10g Dataguard, 1 primary and 2 standby, and the
sessions re-establish to the correct primary database- however they are not TAF
compliant so it requires a restart of the app.
-----Original Message----- From: oracle-l-bounce@xxxxxxxxxxxxx[1]
[mailto:oracle-l-bounce@xxxxxxxxxxxxx[2]] On Behalf Of Gerry Miller Sent:
Friday, December 16, 2011 12:24 AM To: oracle-l@xxxxxxxxxxxxx[3] Subject:
Switchover of Logical Standby database Hi I have had some experience with
physical standby databases and the Data Guard broker but have recently been
asked to implement a logical standby on 10.2.0.4 on Windows 2008 Server. I was
quite surprised to find that when a switchover or failover is performed that
the databases are not shutdown, which results in a faster operation.
However, I was perturbed to find that any sessions that were originally on the
primary remained on the same database, that is, ended up on the standby
database, when I would have expected them to be on the new primary. Queries can
still be executed but any attempts at DML result in : "ORA-16224 DatabaseGuard
is enabled". This seems an unlikely situation and I can't help but feel that I
must have something wrong with the configuration, although I can't imagine that
it would work at all if that were the case. Is this the expected behaviour or
should the sessions have transferred during the switchover? Regards Gerry --
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