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Maximum Protection mode offers the ultimate in data protection. It guarantees no data loss will occur in the event the primary database fails. In order to provide this level of protection, the redo data needed to recover each transaction must be written to both the local (online) redo log and to a standby redo log on at least one standby database before the transaction can be committed.
Maximum Availability mode does not do this so yes, data loss can occur.
Maximum Availability mode guarantees that no data will be lost if the primary fails, but only if a second fault does not prevent a complete set of redo data from being sent from the primary database to at least one standby database.
So if two or more things go wrong with Maximum Availability its possible to lose data.
For additional information see - Data Guard Concepts and Administration 10g Release 2 (10.2) B14239-05
Section 5.6.1 Choosing a Data Protection Mode
Edited by: mseberg on Apr 12, 2012 8:11 AM
Thanks mseberg, the info is really helped me.
but if we choose the maximum protection with flashback enabled with the primary then will there be any performance impact at production site...?
even i saw the primary will be down/hung if IO not closed with atleast one standby site ? please assist ...
The potential performance impact on the Primary is the same with Max Protection and with Max Availability, because both use the log transport mode SYNC when everything is in order.
The point is that the Primary will change to ASYNC transport when no Standby acknowledges the redo with Max Availability.
With Max Protection, that is not so, which is why this Protection Mode is only recommended with at least two Standby Databases.
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