Oracle ASM Interview Questions/FAQs

Interview Questions

1. What is the use of ASM (or) Why ASM preferred over filesystem?
ASM provides striping and mirroring.

2. What are the init parameters related to ASM?
ASM_DISKSTRING = ‘/dev/rdsk/*s2’, ‘/dev/rdsk/c1*’

3. What is rebalancing (or) what is the use of ASM_POWER_LIMIT?
ASM_POWER_LIMIT is dynamic parameter, which will be useful for rebalancing the data across disks.
Value can be 1(lowest) to 11 (highest).

4. What are different types of redundancies in ASM & explain?
External redundancy,
Normal redundancy,
High redundancy.

5. How to copy file to/from ASM from/to filesystem?
By using ASMCMD cp command

6. How to find out the databases, which are using the ASM instance?
ASMCMD> lsct
SQL> select DB_NAME from V$ASM_CLIENT;

7. What are different types of stripings in ASM & their differences?
Fine-grained striping
Coarse-grained striping
select NAME,ALLOCATION_UNIT_SIZE from v$asm_diskgroup;

8. What is allocation unit and what is default value of au_size and how to change?
Every ASM disk is divided into allocation units (AU). An AU is the fundamental unit of allocation within a disk group. A file extent consists of one or more AU. An ASM file consists of one or more file extents.
CREATE DISKGROUP disk_group_2 EXTERNAL REDUNDANCY DISK ‘/dev/sde1’ ATRRIBUTE ‘au_size’ = ’32M’;

9. What are the background processes in ASM?

10. What process does the rebalancing?

11. How to add/remove disk to/from diskgroup?