Introduction to Oracle Data Guard:redo transmission

Data Guard offers two main services:

1 Redo Transport Service: The Primay end of the redo log transmission to one or more standby destinations.

2 Redo Application Service: The redo log which is transmitted from the Primay end is applied to the standby end.

This article first discusses the redo transport services.

1, the use of ARCN transmission redo log

By default, the ARCN transport redo log, but only in the most high-performance mode can use ARCN (specific reference to the "Data Guard-three protection mode"), using the arch transmission redo log diagram is as follows:

Note: The above image from "Dahua Oracle RAC"

The approximate process is as follows:

1 Primay segment ARC0 Once the log switch is completed, ARC1 transmits the newly generated archive log to the standby end;

2 standby driven by RFS process to accept the log, if configured standby redo log, log to standby redo log, and so standby redo log to do log switch to form an archive log, and then apply the archive log for recovery If you do not configure the standby redo Log,rfs process to receive the log, put it in the standby-side archive directory and standby reapply the archive log for recovery.