ORA-01624

      一朋友在删除standby logfile的时候遇到错误ORA-01624，此错误在oracle server-enterprise edition - version:9.2.0.7级以后的版本会遇到。造成ORA-01624错误的原因是：
      1.参数STANDBY_FILE_MANAGEMENT并不影响online redolog。
      2.在primary database中删除了当前使用的或者尚未归档的online redolog。
      具体错误如下：
      SQL> alter database drop standby logfile group 1;
      alter database drop standby logfile group 1
      *
      ERROR at line 1:
      ORA-01624: log 1 needed for crash recovery of thread 1
      ORA-00312: online log 1 thread 1: '/u01/oradata/orcl/redo01.log'
      ORA-00312: online log 1 thread 1: '/u01/oradata/orcl/redo02.log'

      错误ORA-01624在oracle 10g error messagess是这样描述的：
      ORA-01624: log string needed for crash recovery of instance string (thread string).

      Cause: A log cannot be dropped or cleared until the thread's checkpoint has advanced out of the log..

      Action: If the database is not open, then open it. Crash recovery will advance the checkpoint. If the database is open force a global checkpoint. If the log is corrupted so that the database cannot be opened, it may be necessary to do incomplete recovery until cancel at this log.

      为了避免发生次错误，我们在删除redo logfile的时候可以通过查看视图V$LOG，当列STATUS的值为INACTIVE并且列ARCHIVED的值为YES的时候才能删除此redo logfile。解决错误ORA-01624的方法如下：

      1.在primary database上切换日志文件，使此日志文件组状态non-current。       
        SQL> alter system switch logfile;

      2.在操作系统层面将此日志文件组拷贝到standby database所对应的位置。
      3.用操作系统命令将此日志文件组中的一个日志文件拷贝到其他位置
      4.使用下面命令重命名第三步拷贝的日志文件，然后清除此日志文件组
        SQL> alter database rename file 'full_path_old_location/redo_log_name.log' to 'full_path_new_location/redo_log_name.log';
        SQL> alter database clear logfile group;
        SQL> alter database drop standby logfile group 1;