备库不能实时应用的问题

最近搭了一套备份ADG，但是死活不能实时应用，只能应用归档日志，参数方面都没问题：

能实时应用日志的的备库告警日志：

Recovery of Online Redo Log: Thread 1 Group 31 Seq 526638 Reading mem 0
  Mem# 0: /oradata/oratest2/redo31.log
Fri Jul 03 04:17:19 2015
RFS[3]: Selected log 32 for thread 1 sequence 526639 dbid -869801835 branch 753369815
Fri Jul 03 04:17:20 2015
Archived Log entry 244 added for thread 1 sequence 526638 ID 0xd3deef5b dest 1:
Fri Jul 03 04:17:20 2015
Media Recovery Waiting for thread 1 sequence 526639 (in transit)
Recovery of Online Redo Log: Thread 1 Group 32 Seq 526639 Reading mem 0
  Mem# 0: /oradata/oratest2/redo32.log

不能实时应用日志的备库告警日志：

RFS[3]: Assigned to RFS process 46466
RFS[3]: No standby redo logfiles available for thread 1 
RFS[3]: Opened log for thread 1 sequence 10044 dbid -884668 branch 835802052
Fri Jul 03 09:44:55 2015
Media Recovery Log /oradata/uatarch/1_10043_835802052.dbf
Media Recovery Waiting for thread 1 sequence 10044 (in transit)
Fri Jul 03 10:04:12 2015

仔细看发现 No standby redo logfiles available for thread 1  提示，网上一查得到提示：
原因是主库redo 大小为600M，二备库standby log 为500M。

解决办法：

1、停止应用进程

2、删除standby logfile

3、重建standby logfile

4、启用应用进程