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19c Observe-Only Data Guard FSFO: no split-brain risk in manual failover

Fast-Start Failover (FSFO) is an amazing feature of Oracle Data Guard Broker which brings High Availability (HA)features in addition to the Disaster Recovery (DR) one.

Data Guard as an HA solution

By default, a physical standby database protects from Disaster Recovery (like when your Data Center is on fire or underwater, or with a power cut,…). But it requires a manual action to do the failover. Then, even if the failover is quick (seconds to minutes) and there’s no loss of data (if in SYNC), it cannot be considered as HA because of the manual decision which can take hours. The idea of the manual decision is to understand the cause as it may be better to just wait in case of a transient failure. Especially if the standby site is less powerful and application performance will be degraded.

(DESCRIPTION_LIST=(DESCRIPTION=(ADDRESS_LIST=(FAILOVER=YES)(LOAD_BALANCE=NO)

Do you have complex connection strings with DESCRIPTION_LIST, DESCRIPTION, ADDRESS_LIST, ADDRESS and a nice combination of FAILOVER and LOAD_BALANCE? You probably checked the documentation, telling you that FAILOVER=YES is the default at all levels, but LOAD_BALANCE=YES is the default only for DESCRIPTION_LIST. But when disaster recovery and availability is concerned, the documentation is not sufficient. I want to test it. And here is how I do it.

I don’t want to test it with the real configuration and stop the different instances. And I don’t need to. My way to test an address list is to define a tnsnames.ora with the connection string, such as the following:

Storage Replication for Oracle Database and Licensing

While doing my high availability deep dive at Collaborate 12 few weeks ago, I stated that storage replication qualifies for the cold failover licensing rules (see slide #128). During collaborate I spoke to one person at Oracle who definitely knows the rules. Simon Haslam also reached out to me by email pointing out that things...