Ну .... Слышали про FSFO ? Так вот, FSFO работает основательно только со включенным SYNC режимом

The following paragraphs describe the supported availability modes.

Maximum Availability Mode (Oracle Database 10g Rel 2 and later)
In Maximum Availability mode, FSFO guarantees that no transaction that has received a commit acknowledgment will be lost during a failover. The price for this guarantee is increased commit latency ( log file sync waits). 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). Overall commit latency is increased by the round-trip network latency. With increased latency comes decreased throughput; however, in some cases the difference in throughput may be made up by increasing parallelism.

Although redo transfer is synchronous, Maximum Availability mode allows the primary to remain available if the standby database becomes unavailable for any reason (e.g. standby database, host, or network failure, etc.). 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. When the standby becomes available again, the primary and standby re-synchronize and resume synchronous redo transfer.

Maximum Performance Mode (Oracle Database 11g Rel 1 and later)
Oracle Database 11g FSFO adds support for Maximum Performance mode (async redo transfer), providing the flexibility to trade durability for performance. 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. 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. 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. The minimum allowable limit is 10 seconds.

,думете все кто использует FSFO
работают в идеальной сферической системе?

Требования при SYNC не такие прям и невыполнимые, если у вас сеть и такое не может показать, то я бы задумался ...

Естественно FSFO будет работать и с ASYNC и с MaxPerformance , но этого никто не будет делать на продуктивных системах.

Заканчиваю писать в этом треде, думал как то продуктивно обсудить

я 18 лет на многих базах на нескольких работах делаю ASYNC (теперь вы не сможете писать "никто")

И работает все это так, что до сих пор не возникало желания пробовать SYNC.

Это для продуктивности диалога.

А так, да, мы сильно отвлеклись.