Multiplexed control files

Every Oracle database should have at least two control files, each stored on a different disk. If a control file is damaged due to a disk failure, the associated instance must be shut down. Once the disk drive is repaired, the damaged control file can be restored using the intact copy of the control file from the other disk and the instance can be restarted. In this case, no media recovery is required.

The following describes the behavior of multiplexed control files:

• Oracle writes to all filenames listed for the initialization parameter CONTROL_FILES in the database's initialization parameter file.
• The first file listed in the CONTROL_FILES parameter is the only file read by the Oracle database server during database operation.
• If any of the control files become unavailable during database operation, the instance becomes inoperable and should be aborted.