What is the difference between a data guard (Oracle 11g) operating in max performance ASYNC mode and enabling real time apply and a data guard operating in maximum availability SYNC and enabling real time apply?
What is the overhead on performance in both?
Also, does it make sense in enabling real time apply in max performance mode?
Best Answer
In this Oracle page entitled Database High Availability Best Practices it discusses Data Guard Deployment Options:
Requirement of Zero data loss protection and availability for Oracle Database:
Requirement for Near-zero data loss (single-digit seconds) and availability for Oracle Database:
So, yes Maximum Performance (ASYNC transport) and Redo Apply have real meaning, but part of the meaning is that some data can be lost in case of a failure.
You should also consider the network latency for the ASYNC transport target server, since that will also affect responsiveness.