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Changing parameter in RAC node one by one [message #457187]

Fri, 21 May 2010 11:59

nadvi
Messages: 46
Registered: May 2006
Location: Canada

Member

I want to change the following log_buffer parameter in two node RAC cluster.
alter system set log_buffer=5242880 scope=spfile;

To ensure availability, how the command can be issued on each node avoiding any downtime of both the nodes. Means, reflecting the change in one node first after finishing the tasks, do the same on another node.

Thanks.

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Re: Changing parameter in RAC node one by one [message #457188 is a reply to message #457187]

Fri, 21 May 2010 12:13

Michel Cadot
Messages: 68785
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

You can use "sid" option to change the parameter in only 1 node:
alter system set log_buffer=5242880 scope=spfile sid='sid1';

But as log_buffer is a static parameter you can change it for all instances, it will only be taken in account at the next restart and does not impact currently active instance.

Regards
Michel

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Re: Changing parameter in RAC node one by one [message #457189 is a reply to message #457188]

Fri, 21 May 2010 12:19

nadvi
Messages: 46
Registered: May 2006
Location: Canada

Member

Thanks Michel. Concept is clear now Smile

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Re: Changing parameter in RAC node one by one [message #457955 is a reply to message #457188]

Wed, 26 May 2010 09:33

nadvi
Messages: 46
Registered: May 2006
Location: Canada

Member

Hi Michel,

I have another relevant question.

Is it obvious that, shutting down one node of RAC would disconnect all the connected session in node1?
while node 1 is down, reconnecting to RAC establishes the connection to node2 (load balance is ON)

But, is there any way to avoid disconnection of connected sessions from NODE1 while shudown immediate command executed in node1?

Thanks

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Re: Changing parameter in RAC node one by one [message #457967 is a reply to message #457187]

Wed, 26 May 2010 10:11

mkounalis
Messages: 147
Registered: October 2009
Location: Dallas, TX

Senior Member

If you shut down an instance, all connections to that instance will get disconnected. If you have TAF configured at your client, the connections will reconnect to a surviving node. Any select statements in progress will complete, but any uncommitted dml running will have to be re-executed as the transaction will have been rolled back. I would look at the RAC concepts manual for details at docs.oracle.com. You may want to enable FAN via ONS to your client to handle node failures or planned node outages. The client is responsible for handling database connections - there is no automagical movement of connections between rac nodes in the case of a failure or a shutdown.

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