Cintro files

Edit Close. Toggle navigation. Close 1 of 5. The Desert Review Newsletters. Manage your lists. Support Local Journalism. Support Us. Most Popular. This week's poll. In this case, no media recovery is required. If any of the control files become unavailable during database operation, the instance becomes inoperable and should be aborted.

Oracle strongly recommends that your database has a minimum of two control files and that they are located on separate physical disks. One way to multiplex control files is to store a control file copy on every disk drive that stores members of redo log groups, if the redo log is multiplexed.

By storing control files in these locations, you minimize the risk that all control files and all groups of the redo log will be lost in a single disk failure. It is very important that you back up your control files.

This is true initially, and every time you change the physical structure of your database. The methods for backing up control files are discussed in " Backing Up Control Files ". Increasing the values of these parameters increases the size of a control file of the associated database.

Your operating system specific Oracle documentation contains more information about the maximum control file size. The size of the control file changes between some releases of Oracle Database, as well as when the number of files specified in the control file changes. Your operating system specific Oracle documentation contains more information about specifying control files. You can create an additional control file copy for multiplexing by copying an existing control file to a new location and adding the file name to the list of control files.

Similarly, you rename an existing control file by copying the file to its new name or location, and changing the file name in the control file list. In both cases, to guarantee that control files do not change during the procedure, shut down the database before copying the control file.

You can create new control files when all of the control files for the database have been permanently damaged and you do not have a control file backup or when you want to change the database name. All control files for the database have been permanently damaged and you do not have a control file backup. For example, you would change a database name if it conflicted with another database name in a distributed environment.

See Oracle Database Utilities for information about using this utility. The following statement creates a new control file for the prod database a database that formerly used a different database name :. Omitting a file name can cause loss of the data in that file, or loss of access to the entire database.

Use caution when issuing this statement and be sure to follow the instructions in " Creating New Control Files ". If you follow recommendations for control file backups as discussed in " Backing Up Control Files " , you will already have a list of data files and redo log files that reflect the current structure of the database.

However, if you have no such list, executing the following statements will produce one. If you have no such lists and your control file has been damaged so that the database cannot be opened, try to locate all of the data files and redo log files that constitute the database. Any files not specified in step 5 are not recoverable once a new control file has been created.

Moreover, if you omit any of the files that comprise the SYSTEM tablespace, you might not be able to recover the database. One practice is to store a control file copy on every disk drive that stores members of online redo log groups, if the online redo log is multiplexed. By storing control files in these locations, you minimize the risk that all control files and all groups of the online redo log will be lost in a single disk failure.

It is very important that you back up your control files. This is true initially, and at any time after you change the physical structure of your database.

Such structural changes include:. The methods for backing up control files are discussed in "Backing Up Control Files". Increasing the values of these parameters increases the size of a control file of the associated database. This section describes ways to create control files, and contains the following topics:.

The size of the control file changes between some releases of Oracle, as well as when the number of files specified in the control file changes. Your operating system specific Oracle documentation contains more information about specifying control files. You can create an an additional control file copy by copying an existing control file to a new location and adding the file's name to the list of control files. Similarly, you rename an existing control file by copying the file to its new name or location, and changing the file's name in the control file list.

In both cases, to guarantee that control files do not change during the procedure, shut down the instance before copying the control file. For example, you would change a database's name if it conflicted with another database's name in a distributed environment. The following statement creates a new control file for the prod database formerly a database that used a different database name :.

If you follow recommendations for control file backups as discussed in "Backing Up Control Files" , you will already have a list of datafiles and online redo log files that reflect the current structure of the database. However, if you have no such list, executing the following statements will produce one. If you have no such lists and your control file has been damaged so that the database cannot be opened, try to locate all of the datafiles and online redo log files that constitute the database.

Any files not specified in Step 5 are not recoverable once a new control file has been created. Moreover, if you omit any of the files that make up the SYSTEM tablespace, you might not be able to recover the database.

If the database is open, shut down the database normally if possible. In this case, you will need to recover from the loss of the redo logs Step 8.

If you are creating the control file as part of recovery, recover the database. If you have lost online or archived redo logs or datafiles, use the procedures for recovering those files.

This section describes the most common control file usage errors, and contains the following topics:.