Alias Oracle ASM File Name Forms

You can use Alias Oracle ASM file names both for referencing existing Oracle ASM files and for creating new Oracle ASM files. Alias names start with the disk group name preceded by a plus sign, after which you specify a name string. Alias file names are implemented using a hierarchical directory structure, with the slash (/) or backslash (\) character separating name components. You can create an alias in any Oracle ASM directory generated by Oracle Managed Files (system-generated) or created by a user. An alias must include the disk group name; you cannot create an alias at the root level (+).

When you create an Oracle ASM file with an alias file name, the file is created with a fully qualified name, and the alias file name is additionally created. You can then access the file with either name.

Alias Oracle ASM file names are distinguished from fully qualified file names or numeric file names because they do not end in a dotted pair of numbers. It is an error to attempt to create an alias that ends in a dotted pair of numbers, such as in the format USERS.259.685366091. Examples of Oracle ASM alias file names are:

+data/orcl/control_file1
+fra/recover/second.dbf

Oracle Database references database files by their alias file names, but only if you create the database files with aliases. If you create database files without aliases and then add aliases later, the database references the files by their fully qualified file names. The following are examples of how the database uses alias file names:

  • Alias file names appear in V$ views. For example, if you create a tablespace and use an alias file name for the data file, the V$DATAFILE view shows the alias file name.

  • When a control file points to data files and online redo log files, it can use alias file names.

  • The CONTROL_FILES initialization parameter can use the alias file names of the control files. Database Configuration Assistant (DBCA) creates control files with alias file names.

Note:

Files created using an alias file name are not considered Oracle Managed Files and might require manual deletion in the future if they are no longer needed.

For more information about alias file names, see "Managing Alias Names for Oracle ASM File Names".