Re: Question on Oracle 11G RAC

Hi Riyaj,

Thanks for your input. 

"Not that extended cluster is bad, but needs lot more thinking, 
application code changes, configuration issues etc."

I did not understand how there will be application code changes when using 
extended RAC, To my understanding there are some considerations to be 
taken at design part and there are some configurations involved. Could you 
please let me know any issue you foresee specific to extended RAC cluster 
?

Thank You,

Kind Regards,
Sreejith Nair




From:   Riyaj Shamsudeen <riyaj.shamsudeen@xxxxxxxxx>
To:     Sreejith.Sreekantan@xxxxxxxxxx
Cc:     Andrew Kerber <andrew.kerber@xxxxxxxxx>, oracle-l@xxxxxxxxxxxxx, 
rshamsud@xxxxxxxxx
Date:   11/15/2010 11:33 PM
Subject:        Re: Question on Oracle 11G RAC



Sreejith

    I think, what you are describing is a RAC extended cluster. You really 
don't want to do this. Cache fusion locks (BL) will be requested if the 
block is transferred between the instances, it doesn't matter one instance 
is update only and another is read only etc. This configuration will cause 
lot more issues then you are envisioning.

  Not that extended cluster is bad, but needs lot more thinking, 
application code changes, configuration issues etc.
  
   As Andrew said, Active data guard with real time apply is the correct 
solution is for this problem. Not RAC.

Cheers

Riyaj Shamsudeen
Principal DBA,
Ora!nternals -  http://www.orainternals.com - Specialists in Performance, 
Recovery and EBS11i
Blog: http://orainternals.wordpress.com
OakTable member http://www.oaktable.com
Co-author: "Expert Oracle practices: Oracle Database Administration from 
the Oak Table" http://www.apress.com/book/view/9781430226680



On Tue, Nov 9, 2010 at 7:42 AM, Sreejith S Nair <
Sreejith.Sreekantan@xxxxxxxxxx> wrote:
Hi, Thanks for the hint. 
I have a couple of questions. 

In a normal 2 node RAC database environment, will the two instances be 
always active ?  I mean , will cache fusion takes place frequently , If my 
application and DMLs does not user parallelism  ? 
I am just thinking , when will the high speed interconnect becomes busy 
with data transfer 


If I can create a service one each node and associate to instance , How 
does my client tnsnames.ora looks like ? I could not figure out this. 

Appreciate any help on this. 

Kind Regards, 
Sreejith Nair 



From:        Andrew Kerber <andrew.kerber@xxxxxxxxx> 
To:        Sreejith.Sreekantan@xxxxxxxxxx 
Cc:        oracle-l@xxxxxxxxxxxxx 
Date:        11/09/2010 06:57 PM 
Subject:        Re: Question on Oracle 11G RAC 




That approach would work, but in 11GR2 you can active dataguard with real 
time apply, which allows you to have the standby open in read only while 
the logs are being applied.  That seems to be what you really want.

On Tue, Nov 9, 2010 at 2:24 AM, Sreejith S Nair <
Sreejith.Sreekantan@xxxxxxxxxx> wrote: 
Hi friends, 

I have got this question from customer regarding Oracle 11G R2 RAC. 

The customer have stated a preference for configuring the Oracle RAC nodes 
so that, in a two node system, the first node bears all the update load, 
whereas the second RAC node would have connections that are read-only. The 
two nodes would still operate as failovers for one another. The reason for 
this , they stated was to reduce network traffic between the nodes to 
coordinate transactions and locking. They have asked for this 
configuration as 'one update node and one read-only node' / a primary 
update node and a secondary read-only node . 

We have thought about implementing this configuration for our two 
applications as follows 

Application features 

Application 1 - which performs regular updates,heavy transactions,long 
running reports et - schema 1 
Application 2 - performs smalled updates and small reads. - schema 2 

Application 1 can point to node 1 of this RAC and application 2 to node 2 
( using node affinity ).When any of the node fails , the client 
connections will fail over to surviving node. 

I would like to get some recommendations on this approach from experts. 

1) Do you think the above approach using node affinity is a good approach 
, ie pinning one schema in one node with one database for a two 
instance(node) RAC ? 
2) Any documents / reference to configure this approach in RAC ? 
3) Is there any other way to achieve the requirement put by the customer ? 

4) If the above said nodes are in two data centres, Will it be a 
recommended approach ? I think these two nodes should be in same data 
centre. 
5) If we configure Load balancing ( in normal RAC or in the setup 
mentioned above) then that would take considerable network b/w ? 

OS is RHEL 5.4 on 64 bit. 

Please share your view on this. 

Thanks , 
SSN 







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