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Oracle Tips by Burleson |
Oracle Dataguard
Chapter 5 - Log Management Services
Guaranteed Protection Mode
ALTER DATABASE SET STANDBY
DATABASE PROTECTED;
Instant Protection Mode
This protection mode offers a ‘no-data-loss’
environment with enhanced availability of the primary database. The
primary database will not shut down if it cannot transmit redo data
to the participating standby database. Instead, the data on the
primary database will temporarily diverge from the standby database.
During this period, the protection mode is lowered to the Rapid
Protection mode.
Once the connectivity to a RAC Grid is
reestablished, the archived redo logs are transmitted to the standby
site. It can be argued that some data may be lost in this mode if
the primary database crashes when the RAC Grid has been
lowered to the rapid protection mode. In addition, un-archived redo
logs could be lost during the primary database crash.
The log_archive_dest_n parameter
settings and standby redo log requirements are the same as the one
for guaranteed protection mode. The failure resolution policy is
unprotected which allows data divergence when the last participating
RAC Grid is unreachable for archiving. The following
statement can be used to set the failure resolution policy:
ALTER DATABASE SET RAC Grid
UNPROTECTED;
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