发生了这种错误，主库丢失了归档，而备库无法同步日志
Media RecoveryWaiting for thread 1 sequence 70
Fetching gapsequence in thread 1, gap sequence 70-72
Completed: ALTERDATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION
Wed Mar 07 18:26:312012
FAL[client]: Failedto request gap sequence
GAP - thread 1 sequence 70-72
DBID 3857759336 branch 768793323
FAL[client]: Alldefined FAL servers have been attempted.
-------------------------------------------------------------
Check that theCONTROL_FILE_RECORD_KEEP_TIME initialization
parameter is definedto a value that is sufficiently large
enough to maintainadequate log switch information to resolve
archivelog gaps.
-------------------------------------------------------------
1.备库上面查看丢失的归档
idle> SELECTTHREAD#, LOW_SEQUENCE#, HIGH_SEQUENCE# FROM V$ARCHIVE_GAP;
THREAD# LOW_SEQUENCE# HIGH_SEQUENCE#
----------------------- --------------
1 70 72
2.主库查看归档是否存在
先查看文件在系统中的位置
sys@DEX> SELECT NAME FROM V$ARCHIVED_LOG WHERE THREAD#=1 AND DEST_ID=1 AND SEQUENCE# BETWEEN 70 AND 72;
NAME
------------------------------
/u01/arch1/1_70_768793323.arc
/u01/arch1/1_71_768793323.arc
/u01/arch1/1_72_768793323.arc
使用系统命令查看，如果看到没有找到文件，那么进入下面的阶段。
file /u01/arch1/1_70_768793323.arc
/u01/arch1/1_70_768793323.arc:cannot open `/u01/arch1/1_70_768793323.arc' (No such file or directory)
3.备库查看丢失的归档时的scn号
idle> select current_scn from v$database;
CURRENT_SCN
-----------
1102063
4.主库创建基于丢失归档scn号为起始的增量备份（要确定主库和备库的目标目录有足够的空间，这里使用/tmp文件夹）
RMAN> run{
BACKUP DEVICE TYPEDISK INCREMENTAL FROM SCN 1102063 DATABASE
FORMAT '/tmp/stb_bk/%U_for_stb.bk'
include current controlfile for standby ;
}