DG 主库和备库日志大小不一样，无法实时同步数据

一朋友搭建DG，参数没有错误，但是就是无法进行实时同步，，

主库日志：

Destination LOG_ARCHIVE_DEST_2 is SYNCHRONIZED
Destination LOG_ARCHIVE_DEST_2 no longer supports SYNCHRONIZATION
Thread 1 advanced to log sequence 1099 (LGWR switch)
  Current log# 1 seq# 1099 mem# 0: /data/oradata/sch/redo01.log
Sat Dec 26 11:20:20 2015
Archived Log entry 146 added for thread 1 sequence 1098 ID 0xad22dc32 dest 1:

备库日志：

Media Recovery Waiting for thread 1 sequence 1099 (in transit)
Sat Dec 26 11:39:42 2015
Archived Log entry 49 added for thread 1 sequence 1099 rlc 880215476 ID 0xad22dc32 dest 2:
RFS[3]: No standby redo logfiles available for thread 1
RFS[3]: Opened log for thread 1 sequence 1100 dbid -1390233806 branch 880215476
Sat Dec 26 11:39:43 2015
Media Recovery Log /u01/archivelog/arch_880215476_1_1099.arc
Media Recovery Waiting for thread 1 sequence 1100 (in transit)

后来检查发现，主库日志大小为512M，而他备库设置成500M…