从丢失的联机重做日志组的成员中进行恢复。
Recovering from the loss of one member of an online redo log group.
归档日志——联机重做日志的物理副本。
在对联机重做日志进行归档之前，这些日志丢失了。
将所有数据文件、控制文件和联机重做日志文件复制到备份媒介。
Copy all data files, control files and online redo logs file to backup media.
表明例程恢复不再需要联机重做日志组，它可能已经归档也可能未归档。
INACTIVE - Log is no longer needed for instance recovery. It may be in use for media recovery. It might or might not be archived.
联机重做日志组是活动的，但是并非当前联机重做日志组，崩溃恢复需要该状态。
Active - log is active but is not the current log. It is needed for crash recovery. It.
正如名称NOARCHIVELOG所暗示的那样，没有对重做日志进行归档，也就无法像联机重做日志那样支持前滚。
As the name NOARCHIVELOG implies, there is no archiving of redo logs, and thus no rolling forward beyond the online redo logs.
像通过多路复用(放在不同的位置)控制文件使数据库免疫、使用联机重做日志和归档重做日志这样的步骤，都是避免单点故障所必需的。
Steps such as immunizing ther database by multiplexing (putting in different locations) control files, using online redo logs and archiving redo logs are necessary to avoid a single point of failure.
对于联机备份数据文件，这将导致生成大量的重做日志。
This will result in enormous redo logs to be generated for online backup data files.
对于联机备份数据文件，这将导致生成大量的重做日志。
This will result in enormous redo logs to be generated for online backup data files.
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