In addition,
Oracle Data Guard is available only in Oracle Enterprise Edition.
Data Protection Modes
When you configure the primary and standby databases, you will need to determine the level
of data loss that is acceptable to the business. In the primary database, you will define its archive
log destination areas, and at least one of which will refer to the remote site used by the standby
database. The ASYNC, SYNC, ARCH, LGWR, NOAFFIRM and AFFIRM attributes of the LOG_
ARCHIVE_DEST_n parameter setting (see Table 13-1, later in this chapter) for the standby
database will direct Oracle Data Guard to select among several modes of operation:
In maximum protection (or ???no data loss???) mode, at least one standby location must be
written to before a transaction commits in the primary database. The primary database
shuts down if the standby database??™s log location is unavailable.
In maximum availability mode, at least one standby location must be written to before a
transaction commits in the primary database. If the standby location is not available, the
primary database does not shut down. When the fault is corrected, the redo that has been
generated since the fault is transported and applied to the standby databases.
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478 Oracle Database 11g DBA Handbook
In maximum performance mode (the default), transactions can commit before their redo
information is sent to the standby locations. Commits in the primary database occur as
soon as writes to the local online redo logs complete.
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