Data Guard #JoelKallmanDay


Apart from Exadata (been working the last 7 years with it) one of my favourite  Oracle products is Data Guard. 

I don't think I need to explain Data Guard

I have been using Data Guard since quite a while, it literally saved customers' business quite a few times. 

It works way better than storage replication, something that gave already quite a bit of issues in the past at some of my customers, for the same reason as why you use RMAN to backup your Oracle Database ; Oracle knows exactly how an Oracle block / redo / transaction looks like and only copies over data to recover that transaction. Storage replications copies over every change also corruptions. 

Before you just a had a physical standby and you had to type all the commands yourself to do a failover / switchover, but then came the Data Guard Broker, one command to type the broker does the rest.

Since 12.1 I don't see a reason not to use the Broker, works really as a charm.

Oracle extended the feature set a lot over the years :

  • we can have a Snapshot Standby : a standby temporarily opened in read write and then flashbacked again to physical standby
  • Active Data Guard : a standby opened in read only and actually applying redo
  • DML Redirection : on Active Data Guard you can do DML of course this should be limited and it is not the goal to run OLTP load on the ADG
  • An observer can be set up to provide automatic failover, called Fast Start Fail Over ( FSFO)

  • reinstate a standby after a failover 
  • ...

If you are serious about your data and DR Data Guard should definitely be on your list.

And think of all our Oracle Stars there in the sky.




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