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Considerations for Creating a Standby Database with OMF Files

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Description

See Oracle documentation to learn how to enable creating of OMF files using database parameters db_create_file_dest, db_create_online_log_dest_n and db_recovery_file_dest:

http://docs.oracle.com/cd/E11882_01/server.112/e25494/omf.htm#i1006164

Make sure you set these parameters in the standby database to enable creation of OMF files.

Dbvisit favours OMF files (vs filesystem non OMF files and ASM aliases) and always attempts to create OMF standby database files when possible.

Set OMF Locations

For Oracle versions 10+ when setting OMF locations db_create_file_dest, db_create_online_log_dest_n and db_recovery_file_dest for the standby database, keep in mind that standby OMF files will be created using the following structure:

<OMF location>/db_unique_name/datafile
<OMF location>/db_unique_name/tempfile
<OMF location>/db_unique_name/controlfile
<OMF location>/db_unique_name/onlinelog

Redo logs and tempfiles are not created for a standby database but the standby control file contains references to the locations. Once the standby is activated, or switched over to become primary, temp files and redo logs will be created in locations specified by the control file. That is why it is important to set these references correctly.

Example

Specify db_create_file_dest=/oracle/oradata for a standby with unique name testdb to create datafiles under: /oracle/oradata/testdb/datafile. DO NOT set db_create_file_dest to /oracle/oradata/testdb. If you do the files will be created under /oracle/oradata/testdb/testdb/datafile.

CSD Considerations

Create OMF Standby Control Files

When prompted to edit database parameters to be set in the standby spfile, choose 2)Edit oracle database parameters for the standby database pfile/spfile, then choose control_files as a parameter to edit and press ENTER leaving the parameter value NULL. DO NOT set the parameter control_files to your OMF location like /oracle/oradata or C:\oradata. OMF control file(s) will be created under OMF location/db_unique_name/controlfile.

Create OMF Standby Datafiles

If a primary datafile is non OMF (non OMF filesystem file or ASM alias), Dbvisit will create a corresponding standby datafile as non OMF. It will set a parameter db_file_name_convert based on the location for the standby datafiles you have provided, in the standby spfile, to place the standby datafile in a correct location.

If a primary datafile is OMF, Dbvisit will not use db_file_name_convert but will create an OMF standby datafile in an OMF location. For filesystem standby, this is always a location set by db_file_name_convert. For an ASM standby, the user can provide a location as an ASM disk group +DG. The datafile will be created under +DG/db_unique_name/datafile.

Create OMF Standby Redo

Reference in the standby ctl file only.

If a primary redo log is non OMF (non OMF filesystem file or ASM alias), Dbvisit will create a corresponding standby redo as non OMF. It will set a parameter log_file_name_convert based on the location for the standby redo you have provided, in the standby spfile, to place the standby redo in a correct location. If a primary redo is OMF, Dbvisit will not use log_file_name_convert but will create an OMF standby redo in an OMF location. For filesystem standby, see Oracle docs for usage of db_create_file_dest, db_create_online_log_dest_n and db_recovery_file_dest parameters. For an ASM standby, the user can provide a location as an ASM disk group +DG. Standby redo will be named "+DG" in the standby control file. If the standby is activated, redo will be created as OMF files under +DG/db_unique_name/onlinelog.

Create OMF Standby Tempfiles

Reference in the standby ctl file only.

If a primary tempfile is non OMF (non OMF filesystem file or ASM alias), Dbvisit will create a corresponding standby datafile as non OMF. It will set a parameter db_file_name_convert based on the location for the standby tempfiles you have provided, in the standby spfile, to place the standby tempfile in a correct location.

If a primary tempfile is OMF, Dbvisit will not use db_file_name_convert but will create an OMF standby tempfile in an OMF location. For filesystem standby, this is always a location set by db_file_name_convert. For an ASM standby, the user can provide a location as an ASM disk group +DG. The tempfile will be created under +DG/db_unique_name/tempfile.

Note: You cannot use the direct copy option of CSD to create a standby database with OMF files. Use the option to backup the primary to a temporary location.

Anna MacNaughtan September 25, 2013 11:52

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