Initialization Parameters for ASM Instances

Initialization Parameters for ASM Instances

 Parameters that start with ASM_ cannot be set in a normal database instance, although they will be present to the show parameter command.

1.Instance_type:

The INSTANCE_TYPE initialization parameter must be set to Oracle ASM for an Oracle ASM instance. This parameter is optional for an Oracle ASM
instance in an Oracle grid infrastructure home.The default is RDBMS.

The following is an example of the INSTANCE_TYPE parameter in the initialization file:

INSTANCE_TYPE = ASM

2.Db_unique_name:

This parameter specifies the unique name for this group of ASM instances within the cluster or on a node. This parameter defaults to +ASM and
only needs to be modified if you are trying to run multiple ASM instances on the same node.

3.ASM_POWER_LIMIT:

The ASM_POWER_LIMIT initialization parameter specifies the default power for disk rebalancing. The default value is 1 and the range of allowable
values is 0 to 11 inclusive. A value of 0 disables rebalancing. Higher numeric values enable the rebalancing operation to complete more quickly,
but might result in higher I/O overhead.

4.Asm_diskgroups:

The ASM_DISKGROUPS initialization parameter specifies a list of the names of disk groups that an Oracle ASM instance mounts at startup.
Oracle ignores the value that you set for ASM_DISKGROUPS when you specify the NOMOUNT option at startup or when you issue the ALTER DISKGROUP
ALL MOUNT statement. The default value of the ASM_DISKGROUPS parameter is a NULL string.The ASM_DISKGROUPS parameter is dynamic.

The following is an example of setting the ASM_DISKGROUPS parameter dynamically:

SQL> ALTER SYSTEM SET ASM_DISKGROUPS = DATA, FRA;

The following is an example of the ASM_DISKGROUPS parameter in the initialization file:

ASM_DISKGROUPS = DATA, FRA

5.Asm_diskstring:

The purpose of this parameter is to limit the set of disks that Automatic Storage Management considers for discovery.
If not specified the entire system is searched for compatible volumes which can lengthen startup time. The parameters default value is NULL.

(This default causes ASM to find all of the disks in a platform-specific location to which it has read/write access.)