Now that I have a working Oracle 10g database (read this steps 1, 2, 3, if you want to know more about it) I can use it as a primary database in an Oracle Data Guard configuration with the other virtual Linux machine created in this step.
What is a Data Guard configuration and when do you have to use it ??!!??
Oracle Data Guard has been designed to provide an efficient disaster recovery solution and gives us the ability to failover in the event of a disaster.
What does it happen if someone/something fisically destroy our previous Rac environment ???
Data Guard can be configured to guarantee no data loss and to minimize downtime of the production database.
How is Data Guard able to provide an efficient disaster recovery solution ??!!??
It simply :) maintains transactionally consistent copies of the primary production database at a remote site.
These copies are called standby databases and can be one of two types: physical or logical.
In my first configuration I will setup a "physical" standby database on my second Linux virtual machine.
What is the difference between a physical and logical standby database ??!!??
A physical standby database is a block-for-block identical copy of the primary database because it is kept in sync with the primary database by using media recovery to apply redo that was generated on the primary database.
Instead a logical standby database is kept in sync with the primary database using the SQL Apply engine. SQL Apply Engine transforms redo data received from the primary into logical SQL statements and then executes those SQL statements against the standby database: so a logical standby database has the same logical information but a different physical structure.
It's important to remember that a logical standby does not support all Oracle datatypes.
You can run this query
select distinct owner, table_nameto see if you are using unsupported objects.
order by owner;
So before setting up a logical standby database, ensure the logical standby database can maintain the data types and tables in your primary database, otherwise your only and best choice is to setup a physical standby database.
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