DataGuard不設(shè)置FAL也自動(dòng)傳送丟失的Archive Log，什么原因？

FunBSD

Oracle 9.2.0.8
手冊和別人的文檔里寫的都是要設(shè)置FAL_Server和FAL_Client
但我試驗(yàn)了一下，不設(shè)置這兩個(gè)參數(shù)，一樣自動(dòng)傳送丟失的Archive Log

standby日志顯示不能獲取gap sequence，但是primary自動(dòng)傳送了gap sequence之后，standby自動(dòng)繼續(xù)恢復(fù)過程。

standby日志：
Media Recovery Log /opt/oracle/oradata/oradb1/archive/1_163.dbf
Error opening /opt/oracle/oradata/oradb1/archive/1_163.dbf
Attempting refetch
Media Recovery Waiting for thread 1 seq# 163
Fetching gap sequence for thread 1, gap sequence 163-163
Trying FAL server:
Error fetching gap sequence, no FAL server specified
Wed Mar 24 13:22:24 2010
Failed to request gap sequence. Thread #: 1, gap sequence: 163-163
All FAL server has been attempted.
Media Recovery Log /opt/oracle/oradata/arch/1_163.dbf
Media Recovery Log /opt/oracle/oradata/arch/1_164.dbf
......

primary日志：
Wed Mar 24 13:22:55 2010
ARC1: Begin FAL archive (thread 1 sequence 163 destination ORADB_STANDBY)
Creating archive destination LOG_ARCHIVE_DEST_2: 'ORADB_STANDBY'
ARC1: Complete FAL archive (thread 1 sequence 163 destination ORADB_STANDBY)

FunBSD

以下是我的想法，不知道對不對

設(shè)置了FAL_Server和FAL_Client，就會(huì)在standby上pull archive log
設(shè)置了FAL_Server和FAL_Client，還可以從其他服務(wù)器上pull archive log，不一定是從primary上

如果不設(shè)置FAL_Server和FAL_Client，那就自動(dòng)從primary向standby push arvhice log