Multiplexed Control Files (68)

As with redo log files, Oracle enables multiple, identical control files to be open
concurrently and written for the same database. By storing multiple control files for a
single database on different disks, you can safeguard against a single point of failure
with respect to control files. If a single disk that contained a control file crashes, then
the current instance fails when Oracle attempts to access the damaged control file.
However, when other copies of the current control file are available on different disks,
an instance can be restarted without the need for database recovery.
If all control files of a database are permanently lost during operation, then the
instance is aborted and media recovery is required. Media recovery is not
straightforward if an older backup of a control file must be used because a current
copy is not available. It is strongly recommended that you adhere to the following:
■ Use multiplexed control files with each database
■ Store each copy on a different physical disk
■ Use operating system mirroring
■ Monitor backups

1. 使用多個同一的控制檔案
2. 多個控制檔案放在不同的物理磁碟上
3. 映象 ， 備份

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