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rac guard 2 documentation and use [message #172669] Wed, 17 May 2006 09:43 Go to next message
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Registered: December 2005
Senior Member
I am new to rac and data guard. where can i find the documentation for rac data guard 2 (for oracle 9i release2)

also what is the purpose of data guard 1 and data guard 2 in combination with rac? is data guard same is standby database? -

also what is the best practice of choosing among these options? if one decides to install rac, should he set up dataguard1 and/or data guard 2 also?

with thanks..
Re: rac guard 2 documentation and use [message #172677 is a reply to message #172669] Wed, 17 May 2006 10:33 Go to previous messageGo to next message
Mahesh Rajendran
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Registered: March 2002
Location: oracleDocoVille
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RAC and data guard are different concepts which may be put to use side-by-side.
But it is not a must.
With RAC, you have one database and multiple instances (spread across multiple hosts).
If one Node N1 fails (Oracle instance in Node1 fails or that Node1 is smoked) the other nodes are still
available and will server the users. Provides a Single-instance-failover and load balancing.
But if the database fails ( say your EMC SAN is under a foot of water) nothing works.

Data guard is a standby (different technology. You can also have a standby using RMAN).
You can have one or more separate DR/Standby site, where you maintain databases that
are constantly synchronized with the primary database.

Both offer High Availability in different levels.
In simple words, you have a data center in Building 1.
You have a 4 node RAC in data center 1. If One of nodes fail,still other 3 will serve.

But if Building 1 cannot be reached/goes down in an emergency,
With data guard you can have another similar setup in Building 2.
With a very short notice you can make data center in Building 2 operational.

Frequently asked question is, why cannot we have 2 nodes in building_1 and nodes in building 2? (only RAC no data guard).
You can.
But if the two buildings are separated by a few hundred miles, you cannot afford running cables across. Right?
And, if database is gone, RAC is of no use.
So a standby database is what you need here. your DR site can be remotely
anywhere( Even in outer space? Smile Kidding. In a reasonable location).

>> where can i find the documentation

You may want to think about 10g RAC/DataGuard. 9i is about to be euthanized.
Re: rac guard 2 documentation and use [message #172826 is a reply to message #172677] Thu, 18 May 2006 03:36 Go to previous message
Messages: 826
Registered: December 2005
Senior Member
These details are most useful to me. My confusions regarding rac and data guard and their interrelation etc are all gone! Thank you so much.

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