Reverting Disk Group Compatibility

Advancing the values for disk group compatibility attributes is an irreversible operation. If you advance the disk group compatibility settings, you cannot change the values back to the previous settings. To revert to the previous values, you must create a new disk group with the old compatibility attribute settings and then restore the database files that were in the disk group to the new disk group.

When you revert to a new disk group with the old compatibility attribute settings, the latest Oracle ASM features might not be available. For example, if you revert the disk group compatibility to a pre-11.2 value, Oracle ACFS functionality is not available.

For example, you could perform the following procedure to revert a disk group to previous compatibility settings:

1. If the Oracle ASM SPFILE is in the disk group, move this SPFILE out of the disk group:

   1. Connect with SQL*Plus to the Oracle ASM instance.

   2. Create a PFILE in the file system.

      For example:

      SQL> CREATE PFILE '$ORACLE_HOME/dbs/asmspfile.ora' FROM SPFILE;
      

2. If the OCR and voting files are in the disk group, move them out of this disk group.

   See Also:

   The Oracle Clusterware Administration and Deployment Guide for information about administering OCR and voting files

3. Back up any files that must be saved.

   1. Back up the database files.

   2. If an Oracle ACFS file system is mounted on an Oracle ADVM volume on the disk group, the operating system files in the file system must be backed up or copied to a location outside the file system mount point.

4. Create a new disk group using SQL CREATE DISKGROUP specifying the previous values for the disk group attribute settings.

   For information about creating a disk group, see "Using the CREATE DISKGROUP SQL Statement".

5. Move or restore the database files into the newly created disk group using either the ALTER DATABASE MOVE DATAFILE SQL statement or Recovery Manager (RMAN).

   For information about moving data files between disk groups, refer to "Moving Data Files Between Disk Groups With ALTER DATABASE".

   For information about moving database files with RMAN, refer to "Moving Data Files Between Oracle ASM Disk Groups Using RMAN".

   See Also:

   Oracle Database Administrator's Guide for information about using the ALTER DATABASE MOVE DATAFILE SQL statement to move data files between Oracle ASM disk groups.

6. Drop the disk group with the advanced disk group compatibility settings using SQL DROP DISKGROUP INCLUDING CONTENTS to remove the disk group and its contents.

   This SQL statement also removes any Oracle ACFS file system and its contents.

   For information about dropping a disk group, see "Dropping Disk Groups".