![]() Flashback Databaseįlashback Database is a continuous data protection (CDP) solution integrated with the Oracle Database. FSFO is a feature of Broker which records information about the failover target, how long to wait after a failure before triggering a failover, and other FSFO specific properties. It automatically sets Data Guard related database initialization parameters on instance start and role transitions, starts apply services for standbys, and automates many of the administrative tasks associated with maintaining a Data Guard configuration. Data Guard Brokerīroker is a Data Guard management utility that maintains state information about a primary and its standby databases. The minimum allowable limit is 10 seconds. For example, if the limit specified is 30 seconds (the default), FSFO guarantees that all transactions that committed prior to 30 seconds ago are preserved during failover. FSFO configurations in Maximum Performance mode may limit potential data loss by specifying the maximum allowable age of transactions that are lost during a failover. Commit latency is not affected by redo transfer, but committed transactions whose redo has not been received by the standby will be lost during failover. Oracle Database 11 g FSFO adds support for Maximum Performance mode (async redo transfer), providing the flexibility to trade durability for performance. Maximum Performance Mode (Oracle Database 11 g Rel 1 and later) When the standby becomes available again, the primary and standby re-synchronize and resume synchronous redo transfer. If the primary is unable to contact the standby after a user specified period of time (NET_TIMEOUT option of log_archive_dest_ n), it drops out of synchronous transfer mode and begins operating as though it were in Maximum Performance mode. standby database, host, or network failure, etc.). With increased latency comes decreased throughput however, in some cases the difference in throughput may be made up by increasing parallelism.Īlthough redo transfer is synchronous, Maximum Availability mode allows the primary to remain available if the standby database becomes unavailable for any reason (e.g. Overall commit latency is increased by the round-trip network latency. Maximum Availability mode uses synchronous redo transfer and FSFO imposes the additional requirement that the redo is recorded in the standby redo log (SRL) of the target standby (AFFIRM option of log_archive_dest_ n). ![]() The price for this guarantee is increased commit latency ( log file sync waits). In Maximum Availability mode, FSFO guarantees that no transaction that has received a commit acknowledgment will be lost during a failover. Maximum Availability Mode (Oracle Database 10 g Rel 2 and later) The following paragraphs describe the supported availability modes. ![]() The standby can be physical or logical and there can be multiple standbys, but only one of the standbys can be the failover target at any given time. The foundation of FSFO is Data Guard - a primary and at least one standby. FSFO builds upon a number of other Oracle technologies and features such as Data Guard, Flashback Database, and Data Guard Broker.
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