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Re: RAC problem, TAF in primary/secondary role?

From: Carel-Jan Engel <cjpengel.dbalert_at_xs4all.nl>
Date: Fri, 22 Oct 2004 11:14:02 +0200 (CEST)
Message-ID: <18436.213.34.28.241.1098436442.squirrel@webmail.xs4all.nl>


Your scenario is very similar to the issue TAF/Data Guard (DG).

There are two ways solving this in a Data Guard environment, I'm not sure whether you can transplant some of it to RAC.

I use n+1 listeners per server. The default listener is the one I use for Data Guard traffic, and this one is always running. The other listener is the 'Application' listener, this one listens on the IP Address/port for the applications to connect. The latter one is created dedicated per instance, and is only started when the instance is running as a primary (In the DG meaning of the word 'primary')

Another way is using different instance-names for different roles. The application will only find the instance that has the correct role, because PMON registered the corresponding name to the listener. This is described in more detail in Metalink note 205637.1

I prefer the first method. I think it is more straightforward, but I might be biased by the fact that it was created by myself. It works for me, especially because I manage DG with my own bunch of scripts. They have an initalisation line which says: export TAF_ENABLED=TRUE. After that it will stop/start the righth listener at the right moment for me automagically.

Regards, Carel-Jan

===
If you think education is expensive, try ignorance. (Derek Bok) ===

> Hi,
>
> i have tested the primary / secondary role, and i
> found some differences when using TAF.
>
> For example when NOT using active_instance_count,
> first i connect to instance A, and then i shutdown
> instance A. From the same session, i check that it was
> failed over to instance B (select * from v$instance).
> Then i startup instance A and shutdown instance B. It
> also failed over back to instance A.
>
> But when i use prim/second role, failover didn't
> worked. I always get error message 'shutdown in
> process' or 'disconnected'.
> So, does TAF not work in this kind of setting? The
> only failover that is success is for connection/logon
> time.
>
> regards,
> tomi
>
> --- Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
> wrote:
>
>>
>>
>> The Global Resource Directory is statically
>> hashed between all available nodes. (Although
>> a cunning implementation allows it to be gradually
>> re-hashed when node counts change).
>>
>> This means that (on average) half the global cache
>> resources for your tablescan will be mastered on
>> the wrong node, so Oracle will need to make cross
>> instance calls to acquire the relevant gc locks.
>>
>> The primary/secondary implementation is a very
>> special case which puts the entire GRD onto just
>> one node, which is the node you must make available
>> as public node. All the GC operations will be
>> local,
>> which will have a significant effect on the
>> tablescan.
>>
>> The secondary node can still be used (e.g. for
>> large-scale
>> maintenance) but every operation will have always be
>> using remote resources, so the instance will run
>> more
>> slowly than you might expect.
>>
>>
>>
>> Regards
>>
>> Jonathan Lewis
>>
>> http://www.jlcomp.demon.co.uk/faq/ind_faq.html
>> The Co-operative Oracle Users' FAQ
>>
>> http://www.jlcomp.demon.co.uk/seminar.html
>> Optimising Oracle Seminar - schedule updated Sept
>> 19th
>>
>>
>>
>>
>>
>> ----- Original Message -----
>> From: "tomi wijanto" <restomi_w_at_yahoo.com>
>> To: "oracle-l" <oracle-l_at_freelists.org>
>> Sent: Friday, October 22, 2004 4:55 AM
>> Subject: Re: RAC problem, is gc_files_to_locks is
>> needed?
>>
>>
>> Hi, thanks for the reply..
>>
>> i only change tnsnames to disable load balancing and
>> enable failover, just like you said on second
>> option.
>> All instances are up.
>>
>> Your third option is very interesting. What is the
>> differences from cache fusion perspective between
>> primary/secondary role and my way, assume all
>> clients
>> always connect to the first instance in their
>> tnsnames?
>>
>> regards,
>> tomi
>>
>
>
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Received on Fri Oct 22 2004 - 04:09:42 CDT

Original text of this message

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