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Need for separate instance in RAC database [message #439481] Sun, 17 January 2010 12:25 Go to next message
Richard2009
Messages: 21
Registered: October 2009
Location: London
Junior Member
Hi Experts,

Currently we have a RAC 11g database with two instances. Our business is requesting to create one more instance with an user to store historical data. They claim that they need this separate Instance for the following reasons

1)Easy backup and recovery for a specific instance in case of historical data
2)Point-in-time recovery is possible
3)If any other node fails, then it won't affect this instance

Please share your expertise on this regard. Thanks in advance.

Regards,
Richard

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Re: Need for separate instance in RAC database [message #439483 is a reply to message #439481] Sun, 17 January 2010 12:29 Go to previous messageGo to next message
Michel Cadot
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You don't need another RAC instance but another database.
Maybe filled by Streams or a logical standby (if you want almost instantaneous updates) or filled with materialized views or transportables tablespaces for deferred updates.

It depends of kind of data (just historical, with current ones or not, with aggregates or not)...

Regards
Michel

[Updated on: Sun, 17 January 2010 12:30]

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Re: Need for separate instance in RAC database [message #439484 is a reply to message #439483] Sun, 17 January 2010 13:06 Go to previous messageGo to next message
Richard2009
Messages: 21
Registered: October 2009
Location: London
Junior Member
Hi Michael,

Thanks for your response. can you please elaborate on why we need separate db for this request? I am not an RAC expert. Your detailed response will help me to understand this scenario in a better manner.

Thanks a lot.

Regards,
Richard

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Re: Need for separate instance in RAC database [message #439485 is a reply to message #439484] Sun, 17 January 2010 13:35 Go to previous messageGo to next message
Michel Cadot
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If I understand you, you need some archival data which will ne used by other people and with other needs in backup and recovery.
The purpose of RAC is on 2 points:
- more power to access the same data from 2 servers
- more availability thanks to the possibility to reconnect the users from a failed server to another one.
What you describe does not match with theses needs.

Regards
Michel

[Updated on: Sun, 17 January 2010 13:36]

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Re: Need for separate instance in RAC database [message #439488 is a reply to message #439481] Sun, 17 January 2010 14:13 Go to previous messageGo to next message
Mahesh Rajendran
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As Michel already stated, you do not need another RAC instance for this.
>>1)Easy backup and recovery for a specific instance in case of historical data
>>2)Point-in-time recovery is possible
Makes no difference.
Efforts are same. You can backup and recover the "original instance".
>>3)If any other node fails, then it won't affect this instance
If Node1 fails, all the instances in node fails.
That means, both the current prod and 'archive' will anyhow be gone.

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Re: Need for separate instance in RAC database [message #439489 is a reply to message #439485] Sun, 17 January 2010 14:14 Go to previous messageGo to next message
Richard2009
Messages: 21
Registered: October 2009
Location: London
Junior Member
Hi Michel,

Our business main concerns are

1) If something goes wrong, we need to bring the data easily - point-in-time recovery

2) First instance is for OLTP and second instance is for DW and they would like to have third instance for "reporting needs"

Please advise whether we need to have a separate instance or a database to accomplish the goal.

Regards,
Richard

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Re: Need for separate instance in RAC database [message #439490 is a reply to message #439489] Sun, 17 January 2010 14:16 Go to previous messageGo to next message
Mahesh Rajendran
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>>2) First instance is for OLTP and second instance is for DW and they would like to have third instance for "reporting needs"
Now that changes whole game plan.

As Michel suggested,
>>Maybe filled by Streams or a logical standby
Streams or standby would be ideal.
But not in the same server.

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Re: Need for separate instance in RAC database [message #439491 is a reply to message #439490] Sun, 17 January 2010 14:42 Go to previous messageGo to next message
Richard2009
Messages: 21
Registered: October 2009
Location: London
Junior Member
Hi Mahesh,

Thanks for your response. Our business is always talking about point-in-recovery of specific table.Let's say if ETL operation has caused failure after flushing the data from a table, then we should be in a position to bring out the data from the backup at any point in time. Please share your thoughts
on this.
Could you please tell me how to setup the logical standby db in a RAC database

Regards,
Richard

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Re: Need for separate instance in RAC database [message #439492 is a reply to message #439491] Sun, 17 January 2010 14:48 Go to previous messageGo to next message
Michel Cadot
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Quote:
then we should be in a position to bring out the data from the backup at any point in time.

It is a standard point in time recovery, there is no problem with it whatever the solution you take for the DW database.
See Database Backup and Recovery Advanced User's Guide

Quote:
Could you please tell me how to setup the logical standby db in a RAC database

It is not a logical database IN a RAC database, it is a logical standby OF a database (RAC or not).
It is well described in the documentation:
http://www.oracle.com/pls/db102/search?remark=quick_search&word=logical+standby&tab_id=&format=ranked

Regards
Michel

[Updated on: Sun, 17 January 2010 14:53]

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Re: Need for separate instance in RAC database [message #439493 is a reply to message #439492] Sun, 17 January 2010 14:59 Go to previous messageGo to next message
Richard2009
Messages: 21
Registered: October 2009
Location: London
Junior Member
Hi Michel,

Thanks for the clarification. Currently we are taking powerful RMAN backup and they don't want to use this strategy. That's why they came up with the separate instance with a user for ETL operations on historical database.

I could not convince them since they told me that this suggestion was given Senior DBA. Being a junior DBA, they are not ready to listen to my talk and I am not at all happy with this suggestion. Could you please advise how to tackle them and justify the proposed method is useless one?

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Re: Need for separate instance in RAC database [message #439510 is a reply to message #439493] Mon, 18 January 2010 00:04 Go to previous message
Michel Cadot
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Quote:
Could you please advise how to tackle them and justify the proposed method is useless one?

Let them read the current topic and post their arguments, we then can show them why they are wrong.

Regards
Michel

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