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 ;
}