Your database is configured in ARCHIVELOG mode, and daily full database backups are taken. RMAN is configured to perform control file autobackups.
Which statement is true about the loss of a duplexed control file?
Your database is configured in ARCHIVELOG mode, and daily full database backups are taken. RMAN is configured to perform control file autobackups.
Which statement is true about the loss of a duplexed control file?
In a database with multiplexed control files, the database instance will abort if one of the control files is lost or becomes inaccessible. This is because the control file is critical for the operation of the database, and Oracle Database requires all control files to be available for writing changes continuously. In such situations, the database will terminate to prevent any data corruption. After restoring a copy of the intact control file from another location to replace the damaged or missing control file, the database can be restarted without needing media recovery, as the remaining control file(s) would still have all the latest information.
Sorry I think D as per DOC Identifying a Lost Control File It is usually obvious when the control file of your database is lost. The database shuts down immediately when any of the multiplexed control files become inaccessible. Also, the database reports an error if you try to start it without a valid control file at each location specified in the CONTROL_FILES initialization parameter. Loss of some but not all copies of your control file does not require you to restore a control file from backup. If at least one control file remains intact, then you can either copy an intact copy of the control file over the damaged or missing control file, or update the initialization parameter file so that it does not refer to the damaged or missing control file. After the CONTROL_FILES parameter references only present, intact copies of the control file, you can restart your database. https://docs.oracle.com/database/121/BRADV/rcmcomre.htm#BRADV89763
I'm agree with D.
Agree, D is correct.
C is correct, you can restore it by just copying the other controlfile to the duplexed controlfile without shutting down the instance.
If you just copy the other controlfile to the duplexed controlfile using cp command without shutting down the instance, then when you shutdown instance or switch redo log or archive redo log, instance will crash. And after that if you try to check the md5 of all controlfiles , you will find out that they are not identical at all. I had test it with 12.1.0.2 in oracle linux. So D is correct.
Answer: D If any of the control files become unavailable during database operation, the instance becomes inoperable and should be aborted. https://docs.oracle.com/database/121/BRADV/osadvsce.htm#BRADV90040 https://docs.oracle.com/database/121/ADMIN/control.htm#ADMIN112
https://docs.oracle.com/database/121/BRADV/osadvsce.htm#BRADV90040 Use the following procedures to recover a database if a permanent media failure has damaged one or more control files of a database and at least one current control file has not been damaged by the media failure. answer : B
lose of control file always consider as media filer
Think about 'duplexed'
lose of control file always consider as media filer
D is correct, since the database writes to all the control files during its operation. If it not found anyone of them, then the database get terminated.. We just need to get the copy or restore the controlfile to the second location and restart the database. Note:The database will be operating only when both the control files are in completely sync otherwise, the db will get crashed. It may be duplexed or triplexed...
C is correct, you can restore it by just copying the other controlfile to the duplexed controlfile without shutting down the instance
D is correct, since the database writes to all the control files during its operation. If it not found anyone of them, then the database get terminated.. We just need to get the copy or restore the controlfile to the second location and restart the database. Note:The database will be operating only when both the control files are in completely sync otherwise, the db will get crashed. It may be duplexed or triplexed...
I think that the right answer is D. Here is the explaination from oracle site. Read this: Multiplex Control Files on Different Disks ----------------------------------------------------------------- Every Oracle Database should have at least two control files, each stored on a different physical 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 behavior of multiplexed control files is this: -The database writes to all filenames listed for the initialization parameter CONTROL_FILES in the database initialization parameter file. -The database reads only the first file listed in the CONTROL_FILES parameter during database operation. -If any of the control files become unavailable during database operation, the instance becomes inoperable and should be aborted. Reference: https://docs.oracle.com/cd/B19306_01/server.102/b14231/control.htm
I would go for C because select status from v$instance is open even you delete control files. Keep in mind that some dictionary tables have problems dba_data_files then you can restore a good control file to bad control file by cp command
option D is correct as per test that I performed. When once control file was damaged, the session didn't terminate unless I issued a log switch command, because during log switch the SCN number gets written to control file. So database instance aborts and we can start database after we copy un-corrupt file to new file name (provided no change in control file locations)