LOG_ARCHIVE_LOCAL_FIRST

LOG_ARCHIVE_LOCAL_FIRST specifies when the archiver processes (ARCn) transmit redo data to remote standby database destinations.

Values:

• true

  Directs the ARCn process to transmit redo data after the online redo log file has been completely and successfully archived to at least one local destination. This is the default value.

  Because the online redo log files are archived locally first, the LGWR process reuses the online redo log files much earlier than would be possible if the ARCn processes archived to the standby database concurrently with the local destination. This behavior is useful when archiving to remote destinations that use a slow network connection, such as a long-distance wide area network (WAN).

• false

  Directs the ARCn process to transmit redo data at the same time the online redo log file is archived to the local destinations. This results in redo data being promptly dispatched to the remote standby database destination.

  Setting LOG_ARCHIVE_LOCAL_FIRST to false is most useful for faster network connections, such as high-speed local area networks (LAN).

If LOG_ARCHIVE_LOCAL_FIRST is set to true, then it is not used on a physical standby database and any database for which the following attributes have been specified in the LOG_ARCHIVE_DEST_n initialization parameter:

• MANDATORY

• LOCAL

• DEPENDENCY (or any database destination that is the target of a DEPENDENCY attribute)

If LOG_ARCHIVE_LOCAL_FIRST is set to true, then it is ignored during certain operations, such as during a switchover, which requires synchronized archival operations. If the destination was explicitly configured to use the log writer process (by specifying the LGWR attribute in the LOG_ARCHIVE_DEST_n initialization parameter), but for some reason the log writer process becomes unable to archive to the destination, then Data Guard will revert to using the ARCn process to complete archival operations using the default behavior, even if LOG_ARCHIVE_LOCAL_FIRST is set to false.

For example, if a standby database problem or a network problem causes the LGWR process to fail, then the ARCn process will complete the archival. Data Guard minimizes the effect on the primary database as much as possible by archiving to the local destination first to ensure the online redo log files are available to the LGWR process as quickly as possible.