ASM instance initialization Parameter in Oracle

Following are the parameter used in pfile/spfile of Oracle Database:

1. INSTANCE_TYPE: Defines the instance type is RDBMS for Database instance and ASM for ASM instance.

For ASM instance, INSTANCE_TYPE = ASM

2. DB_UNIQUE_NAME: Global Unique name of Database mounted ASM Diskgroups.

DB_UNIQUE_NAME = +asm

3. ASM_DISKGROUPS: It specify the list of diskgroup names that ASM instance going to mount on startup.
Command in SQL ALTER DISKGROUP ALL MOUNT worked on this parameter.

ALTER SYSTEM SET ASM_DISKGROUPS = DATA, FRA;

4. ASM_DISKSTRING: used to specify the list of disks with comma-delimited strings like wild card * used to fetch all disk at specific location.

ASM_DISKSTRING = '/dev/rdsk/*', '/dev/rdsk/*disk4'

5. ASM_POWER_LIMIT: specifies the default power for disk rebalancing in a disk group.

Range from 0 to 1024, 0 value is used for disable rebalance operation.
ALTER SYSTEM SET ASM_POWER_LIMIT = 2;

6. ASM_PREFERRED_READ_FAILURE_GROUPS : is a comma-delimited list of strings that specifies the failure group.

ASM_PREFERRED_READ_FAILURE_GROUPS = diskgroup_name1.failure_group_name1, .. ;
ALTER SYSTEM SET ASM_PREFERRED_READ_FAILURE_GROUPS = DATA,DATA_FG, DATA1, DATA1_FG;

7. DIAGNOSTIC_DEST: It is the directory where diagnostics for an instance are located. Default location of Oracle base is GRID home installation.

ls $ORACLE_BASE/diag/asm/+asm/+ASM