With the introduction of Deferred Durability, this new feature offers a means to ensure that the transaction log is flushed periodically. A new configuration entry was created to indicate the maximum amount of time that will elapse between log flushes:
This keyword takes as an argument the maximum number seconds, N, that will elapse between log flushes. This in turn ensures that after a commit, the log will be flushed in no more than N seconds.
If DELAYED_DURABILITY is used when deferred Durability is not active, one of these two notices will be in the status file:
NOTICE: DELAYED_DURABILITY in use, while MIN_LOG_SYNC not in use
NOTICE: DELAYED_DURABILITY in use, without ctFeatLOGFLUSH_MOD support