ASM_DISKGROUPS specifies a list of disk group names that an Oracle ASM instance mounts 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.

Oracle ASM automatically adds a disk group to this parameter when the disk group is successfully created or mounted, and automatically removes a disk group from this parameter when the disk group is dropped or dismounted.

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