Status of the log member:
  (1).INVALID - File is inaccessible(文件不可访问);

  (2).STALE - File's contents are incomplete(表明该文件内容不完全,例如正在添加一个日志文件成员)
         If the redo log file group member has never been used, either due to a new redo log file group or a repaired member, the value of STATUS is STALE until the log file member is used to record redo information.

  (3).DELETED - File is no longer used(该文件已不再使用);

  (4).null - File is in use(文件正在使用中).
  Log status:
  (1).UNUSED - Online redo log has never been written to. This is the state of a redo log that was just added, or just after a RESETLOGS, when it is not the current redo log.
         (表明从未对联机重做日志组进行写入,这种状态的日志文件要么而是刚增加的,要么是当日志不是current redo log时RESETLOGS操作后的状态)

  (2).CURRENT - Current redo log. This implies that the redo log is active. The redo log could be open or closed.

  (3).ACTIVE - Log is active but is not the current log. It is needed for crash recovery. It may be in use for block recovery. It may or may not be archived.
  (4).CLEARING - Log is being re-created as an empty log after an ALTER DATABASE CLEAR LOGFILE statement. After the log is cleared, the status changes to UNUSED.
         (表明在ALTER DATABASE CLEAR LOGFILE 命令后正在将该日志重建为一个空日志,日志清除后其状态更改为UNUSED。)
  (5).CLEARING_CURRENT - Current log is being cleared of a closed thread. The log can stay in this status if there is some failure in the switch such as an I/O error writing the new log header.
  (6).INACTIVE - Log is no longer needed for instance recovery. It may be in use for media recovery. It might or might not be archived.