To use Oracle ASM, you must first create disk groups with ASMCA before creating a database with DBCA. You can also use the disk group management commands to create and manage an Oracle ASM instance and its associated disk groups independently of creating a database. You can use Oracle Enterprise Manager or DBCA to add disks to a disk group, to mount a disk group or to mount all of the disk groups, or to create Oracle ASM instances. Additionally, you can use Oracle Enterprise Manager to dismount and drop disk groups or to delete Oracle ASM instances.
Oracle ASM instances are created when you install Oracle Clusterware. To create an Oracle ASM disk group, run ASMCA from the Grid_home/bin directory. You can also use the Oracle ASM Disk Groups page in ASMCA for Oracle ASM management. That is, you can configure Oracle ASM storage separately from database creation. For example, from the ASM Disk Groups page, you can create disk groups, add disks to existing disk groups, or mount disk groups that are not currently mounted.
See Also:
Oracle Automatic Storage Management Administrator's Guide for information about managing Oracle ASM
When you start ASMCA, if the Oracle ASM instance has not been created, then ASMCA prompts you to create the instance. ASMCA prompts you for the sysasm password and the ASMSNMP password.