ASM_DISKGROUPS specifies a list of disk group names that an Oracle ASM instance mounts at startup when the ALTER DISKGROUP ALL MOUNT statement is issued.

Property Description

Parameter type



ASM_DISKGROUPS = diskgroup [, diskgroup ] ...

Default value

There is no default value.



Modifiable in a PDB


Range of values

Comma-separated list of strings, up to 30 characters



Oracle RAC

Multiple instances can have different values.


This parameter may only be specified in an Oracle Automatic Storage Management (Oracle ASM) instance.

The Oracle ASM instance startup process executes ALTER DISKGROUP ALL MOUNT unless the NOMOUNT startup option is specified.

The ASM_DISKGROUPS parameter is dynamic. If you are using a server parameter file (SPFILE), then you do not have to manually alter the value of ASM_DISKGROUPS in most situations. Oracle ASM automatically adds a disk group to the parameter when the disk group is successfully created or mounted. Oracle ASM also automatically removes a disk group from the parameter when the disk group is dropped. However, the SPFILE is not updated on a manual dismount.

Issuing the ALTER DISKGROUP...ALL MOUNT or ALTER DISKGROUP...ALL DISMOUNT command does not affect the value of this parameter.

Supporting Up to 511 Disk Groups for an Oracle ASM Instance

In Oracle Database 12c Release 1 or later, Oracle ASM configurations support up to 511 disk groups. Oracle ASM configurations with Oracle Database releases before 12c Release 1 can only support up to 63 disk groups.

See Also:

Oracle Automatic Storage Management Administrator's Guide for more information about and examples of using this parameter