How to manage Control Files??
have discussed briefly the role of control file in an Oracle Database.
The maximum control file size is operating system specific. See your operating system-specific Oracle documentation for more information and try to manage the control file size always within those limits.
The size of the control file can be limited by setting the initialization parameter CONTROL_FILE_RECORD_KEEP_TIME.
The default value is 7. Set it to 0.
CONTROL_FILE_RECORD_KEEP_TIME specifies the minimum number of days before a reusable record in the control file can be reused. In the event a new record needs to be added to a reusable section and the oldest record has not aged enough, the record section expands. If this parameter is set to 0, then reusable sections never expand, and records are reused as needed.
Check v$controlfile_record_section for your knowledge
that the control file is to be always available to Oracle for an OPEN
If you do not specify files for CONTROL_FILES before database creation, and you are not using the Oracle Managed Files (OMF is to be discussed at a later point) feature, Oracle creates a control file and uses a default filename. The default name is operating system specific.
Every Oracle database should have at least two control files, each stored on a different disk. If a control file is damaged due to a disk failure, the associated instance must be shut down. Once the disk drive is repaired, the damaged control file can be restored using the intact copy of the control file from the other disk and the instance can be restarted. In this case, no media recovery is required.
Never ever forget to multiplex the control files.
Recreating Control files
Only recreate the control file under very special circumstances:
All current copies of the control file have been lost or are corrupted.
Never attempt to clone the database
What are the default values of MAXDATAFILES??
The default and the range of values of maxdatafiles and db_files are
Why is there a limit on MAXDATAFILES?
Each platform uses a port-specific number of bits to store the ORACLE file numbers. Thus, this number limits MAXDATAFILES.
What are the limits on MAXDATAFILES?
would one set MAXDATAFILES to anything less than the port-specific maximum?
would one set DB_FILES to anything less than MAXDATAFILES?
Check your ORACLE Installation and User's Guide. The index should point to a port-specific limit.
How can I determine where my CONTROL FILE(s) are?
In SVRMGR (if you are using Oracle 8.1.7 or lesser version) or SQL*PLUS depending on the version (hope you know that SVRMGR is not available in Oracle 9 or higher versions),
show parameter control_files;
If you have multiple control files, you may find that some of them may be cut off in the output from show parameter. In this case, you can query from V$CONTROLFILE;
What common error messages I may get if I exceed the limits???
cannot add any more database files: limit of 32 exceeded
Then, how can I resolve them??
are various options. Metalink Doc ID 119507.1 is best suggested for a
close reading. A discussion on this is relevant when we discuss the backup