Oracle Database 11 g - Online Public Access Catalog

CHAPTER 6 ■ BACKUP AND RECOVERY 291structure on a different host, you can use identical database file names as the source database.You must specify the nofilenamecheck clause in the duplicate database command when youdo this to avoid errors. If the duplicate host uses a different directory structure or you want torename the database files for some reason, you must adopt a strategy to generate the new datafilenames during the database duplication process.The simplest way to generate file names is to specify the spfile clause in the duplicatecommand, as shown here:duplicate database...spfile...The spfile clause lets you set all the file name–related parameters (except the db_file_name_convert parameter). If you’re using the backup-based duplication method, RMAN restoresthe server parameter file from a backup of the source database server parameter file. If you areusing the active database duplication method, on the other hand, RMAN will copy the serverparameter file currently being used by the source database. RMAN copies or restores this spfileto the default location for the auxiliary instance on the host where it’s running. If you don’tspecify the spfile clause, you must copy the server parameter file yourself. You can also specify anormal text-based initialization parameter (pfile) by specifying the pfile parameter instead ofthe spfile parameter as part of the duplicate command.■Tip Oracle recommends specifying the spfile clause in the duplicate command for both backupbasedduplication as well as the new active database duplication technique to set all the necessary parametersinvolving file names and even other initialization parameters such as memory_target, sga_target, and so on.You can provide values for the parameter_value_convert clause when you use the spfile tospecify all path names except the db_file_name_convert and log_file_name_convert parameters.The real purpose of the parameter_value_convert clause is to set the values of a bunch of initializationparameters when creating the duplicate database. RMAN will update the initializationparameter values in the spfile it copied (or the backed-up spfile if you are using the backup-methodof duplication) based on the values you provide for the parameter_value_convert and setparameters. RMAN will then start the new duplicate (auxiliary) instance with the updatedserver parameter values.If you specify the spfile clause with the duplicate command, you must have started theauxiliary instance already with a text-based initialization parameter file (with one requiredparameter, db_name). If you haven’t specified the from active database clause in the duplicatecommand, RMAN will copy the binary server parameter file and restart the auxiliary instancebased on the modified settings gathered from the spfile clause. If you specify the from activedatabase clause in the duplicate command, then the source instance must be using a serverparameter file.If you don’t want to use the spfile clause technique for naming the duplicate files, you canuse alternative file-naming techniques. You can also choose to use the spfile clause to namethe files and supplement that technique with one or more of the alternative techniques.