Thread 1 cannot allocate new log, sequence 71362
Checkpoint not complete
  Current log# 3 seq# 71361 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO03.LOG
Thread 1 advanced to log sequence 71362 (LGWR switch)
  Current log# 1 seq# 71362 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO01.LOG
Sat Jul 17 17:37:22 2010
Thread 1 advanced to log sequence 71363 (LGWR switch)
  Current log# 2 seq# 71363 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO02.LOG
Thread 1 advanced to log sequence 71364 (LGWR switch)
  Current log# 3 seq# 71364 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO03.LOG
Sat Jul 17 17:37:38 2010
Thread 1 advanced to log sequence 71365 (LGWR switch)
  Current log# 1 seq# 71365 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO01.LOG
Sat Jul 17 17:38:22 2010
Thread 1 cannot allocate new log, sequence 71366
Checkpoint not complete
  Current log# 1 seq# 71365 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO01.LOG
Thread 1 advanced to log sequence 71366 (LGWR switch)
  Current log# 2 seq# 71366 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO02.LOG
Thread 1 advanced to log sequence 71367 (LGWR switch)
  Current log# 3 seq# 71367 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO03.LOG
Sat Jul 17 17:38:42 2010
Thread 1 advanced to log sequence 71368 (LGWR switch)
  Current log# 1 seq# 71368 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO01.LOG
Sat Jul 17 17:39:24 2010
Thread 1 advanced to log sequence 71369 (LGWR switch)
  Current log# 2 seq# 71369 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO02.LOG
Thread 1 cannot allocate new log, sequence 71370
Checkpoint not complete
  Current log# 2 seq# 71369 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO02.LOG
Thread 1 advanced to log sequence 71370 (LGWR switch)
  Current log# 3 seq# 71370 mem# 0: D:\APP\ADMINISTRATOR\ORADATA\ORCL\REDO03.LOG

最近经常需要用EXP,IMP迁移数据，alert文件里有这样的告警信息。这种告警说明，ORACLE在切换日志的时候，发现日志所对应的赃数据还没有被写入磁盘，因此必须等到日志所对应的赃数据被写入磁盘才能成功切换。通常的办法可以通过加大日志的大小，加大日志组的数目，减少日志组的成员数，增加dbwn进程的个数来解决。